Is the clutch pedal return spring and the over center spring the same thing?

i just came across this in another thread, i had no idea you had to ditch the over center spring when using a diaphragm clutch. My question is, is the clutch pedal return spring and the over center spring the same thing? My spring that goes around the end of the clutch pedal is still in and i have a diaphragm clutch, but it doesnt seem like the spring helps the clutch pedal down, seems to help pull it back up. Shifts fine but will removing this spring make the pedal not return all the way up? Ive looked through some threads but havent seen what exactly they are refering to by over center spring.