It relates to points.com the company, not points.com the website.

Points.com the company executes, for example, all the BuyAAMiles transactions you do as well as AA to HH or AA to DC transfers (RedeemAAMiles) you do starting at the aa.com website. It does this and other similar "famred out" miles/points services for a number of companies. I'm pretty sure this is what was meant by "wholesale".

So half the "other" means to swap miles are actually implement by points.com behind the scenes.

"Retail" is the stuff you see actually at points.com. Their main business there seems to be sending out tons of emails about useless poor-value stuff most people ignore. At least that was the case prior to GPX; maybe there are some people who find at least GPX useful? (Prior to that, the only thing I ever heard of any FTers finding useful about it was signup and/or Gold upgrade bonuses, on the infrequent occasions that they were better than average.)

The means to swap miles are extermely dependent on the airline/hotel companies involved. Obviously, you can generally swap from most hotel points to many airlines right at the hotel sites. AA, CO, MW, and maybe a few other airlines (but not many) allow swapping to somewhere (that allows, a transfer or two later, to swap back to another airline), AA through Hilton HHonors and Diners Club at least, CO and MW through Amtrak Guest Rewards.

But for some airlines (for example Frontier), the "retail" points.com is the only place you can move out of them (but always at a tremendous loss of value).