How the dictionary defines both:
Leader: 2 : a person who leads : as a : GUIDE, CONDUCTOR b (1) : a person who directs a military force or unit (2) : a person who has commanding authority or influence c (1) : the principal officer of a British political party (2) : a party member chosen to manage party activities in a legislative body (3) : such a party member presiding over the whole legislative body when the party constitutes a majority.
Manager: one that manages : as a : a person who conducts business or household affairs b : a person whose work or profession is management c (1) : a person who directs a team or athlete (2) : a student who in scholastic or collegiate sports supervises equipment and records under the direction of a coach.
Two key words that glaringly define the difference between these two works:
Leader: a person who has commanding authority or influence
Manager: Person who directs
More food for thought!!
Cheers,
Stacey