Mendes is a decorated wrestler and his shot is great. There haven't been many fighters in MMA with that kind of wrestling shot to get singles and doubles. He does beautifully turn the corner, can transition from a single to a double with ease, go high with a body lock and get the slam, run the pipe, chain wrestle, everything you'd expect a high level wrestler to be able to do. RDA's wrestling is good (for MMA) but pretty basic.
One thing that is noticeable about RDA though is that he telegraphs his punches a lot. Robin Black mentioned this on Rogan's podcast recently and he said that he doesn't like criticizing fighters at all but it's something he can't not notice and just forget about. With a striker as lethal as Conor (or Wonderboy, nice AV btw), you can't afford to telegraph your shots. Both guys will absolutely need to be on their A game on the 5th because they're both strong finishers and powerful, athletic fighters.