No, SpellcastingSpellcasting and Pact Magic are distinct features.
As you have observed, the feat Eldritch Adept makes this distinction apparent in its prerequisite:
Spellcasting or Pact Magic feature
“Spellcasting” is the name of the class feature that provides wizards and other casters with the ability to cast spells. However, warlocks have no feature called “Spellcasting”, but they do have a feature called “Pact Magic”. So a warlock cannot take a feat requiring a class feature called “Spellcasting” because they have no such feature.