If you remember Nemesis in Resident Evil, he didn't look like he was created in the same means as the Tyrant. In fact, he has the tentacle parts that seem to be seen a lot throughout the game.
Nemesis was also created in Umbrella Europe, basically where RE4 takes place at. Also, if you recall, despite being like a boss, Nemesis takes a lot of damage before ou "defeat" him, and he still keeps coming back, just like those FREAKY regenerators that you see later on in RE4, where you needed the thermal scope to kill them (otherwise you're using up almost all of your ammo killing one, whether you have a lot of magnum rounds or not).
Nemesis was also created in Umbrella Europe, basically where RE4 takes place at. Also, if you recall, despite being like a boss, Nemesis takes a lot of damage before ou "defeat" him, and he still keeps coming back, just like those FREAKY regenerators that you see later on in RE4, where you needed the thermal scope to kill them (otherwise you're using up almost all of your ammo killing one, whether you have a lot of magnum rounds or not).