On all platforms, a like and a boost communicate two things:
1) I enjoyed this! (Enjoy)
2) Other people should see this! (Visibility)
On a platform like TikTok, the "like" button gives a score of 1.0 to "Enjoy" and N<1.0 to "Visibility." TikTok gives the "repost" button a score of N>0.0 to "Enjoy" and N<1.0 to "Visibility."
Mastodon gives the "like" button a score of 1.0 to "Enjoy" and 0.0 to "Visibility." It gives boost a score of 1.0 to "Enjoy" and a score of 1.0 to "Visibility."