One is using Hexadecimal numbers and the other is using Color names. I suggest using one that is most comfortable to you and sticking with it thru out your web site. Back top Hexadecimal Codes Colors that are defined by a number is called hexadecimal.
Hexadecimal codes can be tricky but some find easier to use.
I have provided a color chart at the bottom of this page to help you out with the color codes. I also suggest you try and use basic colors since there are people out there that cannot see all the color properly. Other browsers may not see the color correctly and can become spotty. They will cover the text, links, visited links, activated links, and background. They are written together in the body tag.