As has been mentioned both are converted safeties, and both guys can really run. Holloman has good speed for a LB. Gooden has good speed for any position. I don't see 4.3 in his future, but he can run sub 4.5, I'm sure.
Gooden is probably going to be the fastest LB at the combine. Think Zach Brown speed. But he's not very big and he's a guy that will get swallowed up by NFL offensive linemen, and understandably tries to avoid taking on blockers at the POA. Had a really good soph year at WLB, but hasn't shown a ton of improvement overall. But is a guy that fits very well in cover 2 and sideline-to-sideline scheme defenses. Good blitzer and potentially a 3-down LB in a couple years.
Holloman isn't nearly as fast, but is very athletic also. He's put on a ton of weight without losing much athleticism, and I think can add a little more weight. Hasn't played LB for very long, but is probably more NFL ready than Gooden at the position. Not stuck at WLB like Gooden, as I think he could potentially play SLB and even MLB in a reserve role. More willing to take on blocks than Gooden. Not as good of a pass defender as one would think as a converted SS. But decent enough as a zone defender. Also an experienced special teamer. He'll start as a backup LB, but I think he can fight to get on the field as a rookie, especially if an injury occurs.