Boost

To boost a post means to "repost" a post onto the timeline of your followers.

Because "boosting" literally means "reposting", those two words are almost used interchangeably.

The only difference being that on many social media platforms, the user is unable to modify the post before boosting it onto their followers' timeline.

A "repost" on the other hand does not require any specific features from a social media platform; only posting either a copy, screenshot, or even "boosting" will suffice in order for that post to be considered "reposted".