For me, what I call a refrain, is a complete thought that can usually be said in 2 bars. I use it to complete a section, and usually as the hook and title.
What I call a chorus, is also a refrain, but the thought needs more than two bars, usually 8 bars but not always. It is also repeated, contains the hook and almost always the title. I sometimes will write 4 bars and finish up each A with them as the refrain. If it doesn't repeat, it's not a chorus or a refrain.
This is that area where terminology fusses up the mix. I use them the same meaning wise. AABA structure, for me, will almost always have what I've come to use as a refrain at the end of the A sections. VCVCBC is really almost the same structure, the refrain is longer.
I think if you listen to the song, AABA will contain the same melody for each A section and a different one for the B section. Using the refrain/title/hook in the A sections will allow me to repeat it more often. I may or may not use it in the B section.
Whereas a VCVC song would have differing melodies in the V and C sections and so would alternate between them more often. Add a bridge with yet another melody and you can put a lot of interesting music together. With the chorus section lasting longer than 2 bars, you have more time to build thoughts and sink a hook.
Sometimes you need to build the refrain, sometimes you don't.
Just about everything I talked about is an arguable point. No, it isn't. Yes, it is.