Just for the sheer hell of it, here's how this theme business often (not always) works in anime.

The short version for TV which nearly always runs 90 seconds these days is called "TV size."

The "full" version is the complete song. A whole song is written first, then shortened to make the 90 second TV theme. This version is often sold as a single and rarely appears on the OST - in order to make more money on each separately.

Then there are the variants - extended versions, remixes, even crazy things like having seiyuus who play characters in the anime sing their own version of the theme. In "Gakkou Gurashi!" (2015), all four schoolgirl characters sang the main TV theme together, but on the multiple OSTs in the box set, each sang their own version of "Friend Shitai", the main theme.

Because if you're a seiyuu in Japan, you had damn well better be able to sing.

When in doubt, use terms like these first and we won't have to deal with this merge foolishness.