Question: What parts do both Dave Matthews and Seo Eunkwang play in their bands?

Context paragraphs:
Dave Matthews Band: Dave Matthews Band, also known by the initialism DMB, is an American rock band that was formed in Charlottesville, Virginia in 1991.  The founding members were singer-songwriter and guitarist Dave Matthews, bassist Stefan Lessard, drummer and backing vocalist Carter Beauford, and saxophonist LeRoi Moore.  Boyd Tinsley joined the band as a violinist soon after the band was formed.  Moore died suddenly in August 2008 due to complications from injuries sustained in an ATV accident.  Grammy Award winner Jeff Coffin (of Béla Fleck and the Flecktones) has since filled Moore's spot as the band's saxophonist; trumpeter Rashawn Ross and guitarist Tim Reynolds have also become full-time members of the band.  Other past members include keyboardists Peter Griesar and Butch Taylor.  The group's 2009 album "Big Whiskey & the GrooGrux King", their first after Moore's death, debuted at number one on the "Billboard" 200, earning them their fifth consecutive number-one debut; their most recent album, 2012's "Away from the World", debuted at number one on the Billboard chart, making Dave Matthews Band the first group to have six consecutive studio albums debut in the top spot (Metallica would be the second to do so in 2016).  As of 2010, the Dave Matthews Band has sold over 50 million records worldwide.

Bartender (Dave Matthews Band song): "Bartender" is one of Dave Matthews Band's most popular live songs, featured on their studio album "Busted Stuff".  The song was one of the many that carried over from the near-abandoned project that is "The Lillywhite Sessions".  If "The Lillywhite Sessions" album is considered a Dave Matthews Band studio album, then "Bartender" is the longest Dave Matthews Band song recorded, and the only one over ten minutes.

Seo Eunkwang: Seo Eun-kwang (; born November 22, 1990), also simply known as Eunkwang, is a South Korean singer, entertainer, and the leader and main vocalist of the South Korean boy group BtoB.

Gravedigger (song): "Gravedigger" is a song by Dave Matthews from his debut solo album, "Some Devil".  This was the first solo single released by Matthews away from the Dave Matthews Band, and it won a Grammy Award for Best Male Rock Vocal Performance at the 46th Grammy Awards held on February 8, 2004.  The song has been performed live by Dave Matthews (solo), by Dave Matthews with Tim Reynolds, at Dave Matthews & Friends concerts, and occasionally as an acoustic solo by Matthews during Dave Matthews Band shows.  During the Dave Matthews Band's tours in 2008 and 2009, it was played regularly by the full band.

Some Devil: Some Devil is the debut solo album by musician Dave Matthews.  It was released on September 23, 2003 on RCA Records.  It has been certified platinum by the RIAA, signifying over a million copies sold.  The album features several guest musicians, including long-time Dave Matthews Band collaborator guitarist Tim Reynolds and Phish frontman and guitarist Trey Anastasio.  The album's first single, "Gravedigger," won a Grammy Award in 2004.  "Some Devil" was recorded at Studio Litho in Seattle, Washington, and produced by Stephen Harris, who had previously worked with the Dave Matthews Band on their 2002 album "Busted Stuff".

Live Trax (series): Live Trax is a series of live albums released by Dave Matthews Band's Bama Rags label.  The albums in the series feature performances by Dave Matthews Band and also Dave Matthews and Tim Reynolds.  The majority of the releases are not sold in commercial stores, but rather by means of order or digital download from the band's official website.  The name "Live Trax" is a reference to the former Trax Nightclub in Charlottesville, Virginia, where the band played over one-hundred twenty shows during their early years from 1991-1996.

Remember Two Things: Remember Two Things is an album by the Dave Matthews Band, released independently on the band's Bama Rags label on November 9, 1993.  This is the only release that lists the name of the group as ""The" Dave Matthews Band."  It was reissued by RCA Records on June 24, 1997 and was certified platinum by the RIAA in 2002.  The album cover art is an autostereogram which, when focused on correctly, shows a person's hand displaying a peace sign.  It was created by two former UVA students in Charlottesville: Rick Kwiatkowski and Jeff Smith.  The general consensus among Dave Matthews Band fan websites is that the two things referred to in the title are "love your mother" and "leave only footprints" as well as the two fingers displayed in the aforementioned cover.

Dave Matthews Band Caravan: Dave Matthews Band Caravan was a series of concert festivals headed by the Dave Matthews Band.  The four festivals, occurring during the summer of 2011, took the place of DMB's usual summer tour, after the band announced its intentions to take time off from touring the previous year.  The first festival took place at Bader Field in Atlantic City, New Jersey.  The second festival was at Chicago's Lakeside.  The third stop of the DMB Caravan took place at Governors Island in New York, New York, but was rescheduled after Hurricane Irene hit the New York area the same weekend.  On September 1, it was announced that the dates were rescheduled, while the venue changed to Randall's Island.  The last stop was The Gorge in Washington.  Each festival is 3 days long, with each show featuring a full set from the Dave Matthews Band.  Various other acts will be performing on different stages prior to DMB's set.

Dave Matthews and Tim Reynolds: Dave Matthews and Tim Reynolds or Dave and Tim is a musical act composed of Dave Matthews, member of Dave Matthews Band, and Tim Reynolds, member of TR3 and Dave Matthews Band.

Dave Matthews: David John Matthews (born January 9, 1967) is a South African-born American singer-songwriter, musician and actor, best known as the lead vocalist, songwriter, and guitarist for the Dave Matthews Band.  Matthews was born in Johannesburg, and moved frequently between South Africa, the United Kingdom, and the United States while growing up.  Matthews mainly plays acoustic guitar, which he started playing at the age of nine.

Supporting paragraphs: Dave Matthews Seo Eunkwang
Answer: vocalist