These questions are ok, but it is important to understand as as much as you can about manifolds. For each of the categories:
- homotopy types satisfying poincaré duality
- topological manifolds
- sobolev manifolds eg quasiconformal or bilipschitz
- piecewise linear or piecewise differentiable C1, C2, ... Cr.....Cinfinity
- real analytic
- real algebraic
then the multiple types with canonical coordinates - complex manifolds
- symplectic manifolds
- in dimension three those with coordinates so that overlap maps satisfy a global analytic continuation property
one
a] Homotopy Types satisfying Poincaré Duality...
b] Topological Manifolds...
c] Sobolev Manifolds eg Quasiconformal or Lipschitz Manifolds...
d] Piecewise Linear or Piecewise Differentiable Manifolds...
e] C1, C2,...C-infiniy = Smooth Manifolds...
f] Real Analytic Manifolds...
g] Real Algebraic Manifolds...
The types with canonical coordinates:::
h] Poisson Manifolds...
i] Symplectic Manifolds...
j] Complex Manifolds...
k] Generalized Complex-Symplectic manifolds...
l] Geometrized Three-Manifolds...
One knows contexts where each of these categories are particularly useful. dennis sullivan
[Dennis Sullivan]