There are many ad formats on Snapchat Ads.
Snap Ads (ads between stories), with a 9:16 ratio and a resolution of 1080×1920 pixels for images or videos
Story Ads (ads in the discover tab), rectangular tile containing several images
Collections Ads (ads between stories), with a ratio of 9:16 and a resolution of 1080×1920 pixels for the presentation of products in the form of thumbnails.
There are also products Ads, lenses, commercial Ads and filters