interesting question!
As of my understading, these two definitions of the components of a sentence, represents two completely different grammatical methodology in analysing/categorizing the components of a sentence...
the “谓语” representing the older one which is also not as scientfic/accurate as the modern one using "述语"...
however, to common user, even us native Chinese speaker, those means pretty much the same... and if you are not living as a scholar of Chinese language study, my suggestion is that you can temporarily treat them as the same...
or dig further...
"述语" may contain Verb and its compliments, quote"I decided what to do" ,,, in this case given by collins...
the old grammatical analysis would say that the "decided" is "谓语"...
whereas in modern Chinese grammatical understanding, the whole phrase“decided what to do” comprise the "述语"...
...gave it my best, hope not making it more confusing... ^^