Actually we found the Aggressor was slightly higher all in. Especially if Explorer has $300 off on the week you're going. I looked at both boats and there are some differences. They may not matter to you, but they did to me. Price is a really minimal difference because Aggressor bundles a fuel surcharge and I believe port taxes in their rate, Explorer you pay it separately. So Explorer's trip price appears initially lower.
Explorer has an extra deck. It's the flying bridge. It's covered, has padded benches and there's small stocked frig. up there. I slept up there a couple of nights. One curved flight of stairs down is the sundeck, it's on top of the dive deck. Explorer vents their compressor thru a slot between the benches on the dive deck and they hung the wetsuit rack above it. So while it's a little awkward on a full boat since you have to reach over people gearing up in front of it, it does a decent job of drying skins/light suits between dives.
Behind the dive deck is the salon/dining room. Behind that are
most of the cabins. They're on the same level. There's two premium cabins upstairs in front of the sundeck and 3-4 below the main level (the cheapest ones) Inside stairs to go up or down also - and to the wheelhouse. There's no public access to the bow and no way to transit around the ship on the main deck as the lounge/cabins extend out to the waterline. Only the lower level cabins have bunks and portholes, everything main deck and above has beds and several large windows. They're big rooms comparitively for a LOB also, ours had a desk in the corner, closet and the bath. I'm 6'4 and could shower but getting thru the shower door was a little tricky since it's glass/metal. Plus a good sized nightstand between the beds. I guess the 2 premier upstairs cabins are even larger. We had #5 - a couple times we felt the heat from the kitchen in the bathroom.
When I looked at the Aggressor, they don't have the flybridge and all their cabins are belowdeck with portholes as is typical with most of their boats. They do have the personal flatscreens afaik. Also they have the hot-tub, Explorer doesn't. When we were on Explorer, they had one of the dinghies stowed on the sundeck, if everyone was down there it made it tight. About 6 of us regularly went up to the flybridge instead. From the Sundeck you can walk to the front of the ship but not around it - there's external access to the wheelhouse and the upper cabins.
What Wookie said, I liked Capt. Ken also. And the rest of the crew. Stan the cook is a legend - as are most lob chefs.
We often moored next to the Aggressor so I don't think either has an advantage there as far as route. I read an Aggressor trip report recently and they named the same dive sites we did. There was a couple days when we didn't see them so maybe the run the route backwards.
What gizmo posted is true for surface interval. If you're spending time b4/after Aggressor's location might be better. Although much of Provo's activity is near Grace Bay anyway. Friday night is dinner off the ship and they need you to leave by around 9AM Sat. We took the crew that could leave to dinner in Grace Bay. It was about a $10 ride in a shared van they schedule. We camped out in the airport restaurant for about 3-4 hrs. since most of our flights left after 1PM. There's wi-fi there. Also wi-fi when you're tied up at the dock.
We arrived early in the afternoon, a crew member met us at the airport, took our gear and had their driver drop us at Salt Mills Plaza for lunch and to look in a few shops. He later picked us up around 4 when the rest of the pax arrived and took everyone to the boat. Probably a 15min. ride from town. Explorer was moored on the south side in a marina next to the police boats - there's maybe one store there and IIRC it was closed. It's shallow so they time the tides to get out/back. Even then we scraped something coming in.
hth, this info is about 2-1/2 yrs. old now. I always provide a link to Mike Southard's excellent trip report. He was there sometime before us.
http://www.awoosh.com/Saudio/Saudio_Turks&Caicos.html