Are kernel trees the same as a branch in terms of git?

Hi guys, there is something I want to know, in the Linux kernel mailing list some developers refer to URLs like these tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master. I doubt that in my learning about git I have not seen any source code called tree so I want to know if a kernel tree is a branch? very thanks :)