I have just come across something that I have never thought about before and it occurred to me that this site would be the place to ask.
The dictionary defines ALLOW as: VERB - let (someone) have or do something.
The dictionary defines LET as: VERB - not prevent or forbid; allow.
So the dictionary uses each word to define the other word. This suggests to me they are likely synonyms.
However if I have this sentence, "doing this allows you to jump higher" I cannot simply just change the word ALLOWS to LETS because the word TO makes the sentence sound wrong; "doing this lets you to jump higher".
Similarly, if I have the sentence "doing this lets you jump higher" and I change the word LETS to ALLOWS, it again sounds wrong; "doing this allows you jump higher".
So my question is, is there a simple reason why, while both words look to be interchangeable at a definition level, choosing either of the words also changes which other words you need in the sentence to make it complete or sound correctly structured?