The phrasal verb 'hook up' can mean a connection or link. You can 'hook up to the grid' for electricity or 'hook up to electricity'. Hook up can also refer to a meeting of people to communicate or cooperate. In a casual colloquial context, to 'hook up' with someone can mean to have a sexual encounter with someone, so be careful about the context you use this phrasal verb in. 

The phrasal verb 'catch up' means to arrive at the same place as someone ahead of you or to complete tasks which have been accumulating. As a noun, a 'catch up' is a meeting between people where they discuss developments or changes from the last time they met. 

1. We should definitely meet for lunch tomorrow. We haven't caught up with each other for so long!
2. I couldn't be bothered going out anywhere this weekend. I'm just going to sit on the couch and catch up on my favourite TV shows.
3. I had a doctor's appointment so I couldn't go to see the movie with Karl and David, but I said that I would hook up with them later.

1. Tom's Manager called him in for a meeting, because he wanted a quick catch-up on his progress.
2. Monday morning at 10 I have a window in my schedule, so we'll have a brief catch-up before continuing with the work.
3. It looks like I won't have the weekend off after all. I just have too much work to catch up on after those sick days I took last week.