Related meta: Merge [resistance] into [damage-resistance]?
However, at the moment, it's not clear what exactly the difference is, or when each tag should be applied. The linked question above has a single response that frankly doesn't explain the difference very clearly or distinguish when either of the two mentioned tags should be used (or what differentiates them from spell-resistance):
Systems have a variety of different types of resistance, including magical, arcane and normal weapons and not all of these relate to damage.
Only damage-resistance has tag info:
The D&D mechanic that represents an ability to shrug off or ignore damage of certain types and amounts.
Damage Resistance is the D&D mechanic that represents an ability to shrug off or ignore damage of certain types and amounts.
It typically represents resilience against mundane attacks or to a specific type of energy. It usually functions as a static reduction of damage taken by the entity. It may be possible to bypass it by some means.
Besides the tag wiki suggesting it's specific to D&D, the description also doesn't seem to match its actual usage in practice.
damage-resistance seems to be used on all sorts of questions relating to resistances (mainly in 5e, and to a lesser degree in 4e and rarely in other systems), whether it's to types of weapon damage, types of spell damage, or damage from other effects. Apparently 85 questions have the tag.
spell-resistance is used much less often; only 9 questions have the tag. All but one of them are for 3.5e or Pathfinder (I'm not very familiar with the systems). This might refer to a unique type of resistance that is separate from what the previous tag covers.
Finally, resistance seems the most generically named of the bunch, and is used on 13 questions. 8 of them are for 5e, 3 for Pathfinder, and 2 for AD&D 2e. Given the generic name, I'm not sure this tag covers any unique situation that's not already covered by the previous two. If it does cover a unique situation, it should almost certainly be renamed, because I think the very nonspecific name is causing it to be used in place of a number of different situations.
Is there a difference between these 3 tags? If so, what is it?
If there is indeed a difference between each of the 3 tags, the tag info should be edited to clarify that difference. If there is no difference between some of the tags, they should be merged (or synonymized, or whatever the proper terminology is).