Nope gods are a lot harder to kill. Archfiends can grant spells but have very little power associated true divinity.
Generally varies by edition and they have elevated fiends to true
Deities.
This, of course, is a critical part of the disagreement here:
Is there such a thing as a "true divinity"? Or is "divine" just a label applied to something that is sufficiently powerful and can perform a particular list of tasks?
For example, in works more influenced by Eastern philosophy/theology, this "true divinity" distinction would be pretty meaningless. Divinity is simply a
status one can achieve through various means, often through becoming "transcendent" in some fashion. E.g., Guan Yu becomes an outright god of war because he's just THAT good at killing people and commanding armies, and even non-divine entities can easily overcome and remove or replace existing deities. The "bureaucracy of heaven" concept plays heavily into this, with the idea that there are courtly positions, titles, etc. that can be gained or lost, transferred, created, etc.
In works more heavily influenced by Western philosophy/theology, on the other hand, divinity is an inherent
nature, and thus "true divinity" can have meaning. Godly status cannot be earned; it is simply present or absent. Some things blur the line a little, e.g. it may be possible to
steal someone else's divine "mantle," or for one or more gods to
promote someone else to divinity, but once they're divine, they're genuinely different from what they were before (and, quite often, this "promotion to divine" usually requires that you meet an inherent prerequisite anyway, like being a demigod or "purging" your mortal aspects or the like.)
In a setting where "true divinity" is an arbitrary or socially-constructed line (even if that line is socially constructed by the gods themselves), there's really no difference. In a setting where "true divinity" really has meaning, where there's a threshold that you either cross or don't cross, then the distinction can matter a great deal. With "true divinity" on the table, even an unmatched demon-prince who can grant spells and otherwise
mimic godhood does not actually
possess godhood, and this may come with various other effects and considerations.