When all else fails, a sense of humour becomes more valued.
At the risk of injecting further confusion into an area where someone is clearly struggling with terminology .... POP in the context of email means 'Post Office Protocol'.
If you want to understand the difference between the two email system (POP and IMAP) and there implications (if any) for your particular usage then I suggest you do your own reading to get it clear in your head.
Of course if you do want to do some basic reading etc. you need the know the correct meaning of the acronym in the first place, otherwise you will be doing reading about 'Point of Presence' and wondering wtf has this got to do with me.