The Rams are paying Miller $700,000 for the rest of the season. And the Broncos are paying him another $9M.
If the Rams could find a team willing to pay JJ while he played for the Rams I'm pretty sure the Rams would have gone for it.
OBJ was on the Browns' initial 53 man roster so his contract for this season is fully guaranteed. He was owed $4.5M for the remainder of the season and if he was picked up on waivers his new team would have had to pay that. But since he cleared waivers the Browns have to pay it. He could have laid on the beach for the next 4 months and he still would have gotten that money. The Rams will give him some token amount on top of that, but it won't be any where near JJ money. Apples and oranges.
AlbaNY_Ram