The same pretty much. I believe that a skimmer is optional at that tank size, again, as long as you take care to do weekly water changes of a decent size, don't overfeed and don't overstock.
The 40 would give you so many more options and would be easier to care for in my opinion.
You also have more lighting choices for a 36" tank on the cheaper side. Some will work for most easy and basic corals and then some. here is an example of the lighting thats on the cheap side but would be sufficient.
The anenome would most likely need a more hi end fixture to keep it healthy and happy. BUT you can also add corals and they may host that instead. My clowns didnt like my nem but loved my elegance coral cause it was so flowy looking. Clowns have been know to host ANYTHING..powerheads, rocks, mushroom corals and anything else they decide on. But it's at best a 50 50 shot of them hosting anything.
I have a pair in my 125g and lots of corals but no hosting yet. BUT it can also take them awhile to do it too. It's not drop a clown in and a nem and boom they host. It does happen but is not the norm.
Is the 40g youre talking about a 40 breeder tank? Cause they are awesome in my opinion. Lots of tank real estate in them so you can have a decent rockscape too. Plus you could add a few other fish other than the clowns and they wouldnt have to be nano fish.
I had 5 fish in my 29g, granted they were all kinda small but the clowns but there was ample room for everyone to do their thing. I had some sand dwellers like a goby, a percher in my blenny and the rock hiding royal gramma. It's all a matter of what fish and their normal habitat. the clowns are my favorite as they explore and swim around constantly usually.
The only other equipment you'd need would be a refractometer for like $30, (much much more accurate than a $15 hydrometer swing arm salinity checker) and for sure a API liquid test kit. If you get heavy on tthe corals some other types of test kits might be necessary like calcium, alaklinity and magnesium. You also could still go with a hang on back filter, but it would have to be rated for over 40g. My personal favorites are the aquaclears. I just got a AC50 for $24 from amazon. Because of the height of the 40b (if thats what you got) I wouldnt think the AC70 would be too good of a fit since it goes quite deep into the tank, but you can always cut down the tube if you wanted to go with the 70.
A skimmer could be a decent hang on back as well if you decided you wanted one. But again, not a necessity imo
on that size tank.