"meet" and "meet up" could be both interchangeable in the sense of seeing and talking with someone familiar you know or someone you don't know at all. " I met a couple of nice people on my way to Berlin " ( Here is unexpectedly ) " I met him at the x coffee as planned for " ( intentionally) " Let's meet up for some drinks after work " ( intentionally) " I met up with her when I left the building " ( unexpectedly ) "Meet up "" could differ slightly to mean coming together in a certain appointed place for a certain aim or to accomplish something as in : "Let's meet up after work to discuss this matter further ". (an arranged meeting with a purpose ). "To meet up to " has a totally different meaning and refers to reaching a certain level of required quality . " He hoped his work meets up to the company's expectation " Apart from having people as subject , 'meet up ' could be the meeting up of roads or streets as in : "The 2 streets meet up at the next intersection " That is basically it ! ;)

"To meet" is to "encounter" and "to meet up" is to "rendezvous."

essentially it means the same thing "would you like to meet" is the same as " would you like to meet up" its more of an American thing to say i guess you could call it slang to some extent.