Divine ranks was a bit of an issue between 1e and 2e.
In 1e's Deities & Demigods, gods were ranked as demigods, lesser gods, or greater gods. As a PC, the main difference between them was what level of spells they could grant (demigods up to 5th, lesser up to 6th, and only greater gods could grant 7th level spells - clerics couldn't go higher than 7th back then). Each pantheon had a smattering of gods at each rank - for example, the Greek pantheon listed Zeus, Aphrodite, Apollo, Ares, Athena, Dionysus, Hades, Hera, Hermes, and Poseidon as greater gods.
Then in 2e you got Legends & Lore, where someone decided that the rank of Greater god should be reserved for the real bigwigs, mainly the heads of the pantheons. But a rank was still needed to distinguish the other "senior" deities from beings like Pan, Tyche, or Hephaestus. So the rank of Intermediate deity was introduced, and in the Greek pantheon only Zeus and Hera (plus some of their titan precursors) kept the rank of Greater god, with the rest "demoted" to Intermediate. So Intermediate basically means "powerful enough to have strong independence, but not the head of the pantheon or a creator-type". Notably for PCs, Intermediate deities could still grant 7th level cleric spells.
But of course, along came Forgotten Realms to blur the issue. Back in 1e, the Faerûnean pantheon mostly stuck with the example set by D&DG: plenty of Greater gods along with a smattering of Lesser and Demigods. In the first 2e description of the pantheon, Forgotten Realms Adventures, those descriptions mostly stuck (probably because FRA preceded Legends & Lore so the Intermediate designation didn't exist yet). But by the time of the 2e FR box set, and particularly by the time of Faiths & Avatars, Intermediate gods were definitely a thing.
Except: unlike most real-world pantheons, there's no boss in the FR pantheon. Well, there's Ao, but they are primarily the god of gods, and don't listen to mortal prayer. So while there are certainly the occasional hierarchies in FR's pantheon (e.g. Tyr being the boss of Torm, or Mystra the boss of Azuth), there's no over-all leader. So who gets to stay a Greater god, and who gets demoted to Intermediate?
Well, turns out that in FR they did it the other way around instead. All the Greater gods kept being Greater, and all (or at least almost all) the gods below got promotions - Lessers became Intermediate, and many (but not all) Demigods became Lesser gods. Oh, and in FR all the gods can grant 7th level spells - the Red Knight may have a significantly smaller amount of power than Tempus, but she also has far fewer clergy to supply.
So that's why FR's divine power structure is wonky compared to other pantheons, and why there's disagreement between sources on which god belongs where. Well, that and the fact that the FR pantheon is an ongoing soap opera that has served as plot in way too many novels.