Splitting or Catfacing? How to avoid?

[luigiwu]

I've googled but I can't seem to differentiate the meaning of catfacing versus splitting...

ANYWAYS, the "splitting" at the stem (at the top) happened at lot last year for me and it looks like its starting to happen again this year? Any ideas how to avoid it? I think I've read it happens with there is too much moisture (rain?) or too hot or too much nutrients?

This is a Prudens Purple below. My first "big" tomato this year!