Let $F\rightarrow E_0 \rightarrow B$ and $F\rightarrow E_1\rightarrow B$ be two smooth fiber bundles. Suppose $E_0$ and $E_1$ are diffeomorphic.
What are the obstructions for $E_0$ and $E_1$ to be diffeomorphic via a bundle map?
To be more specific, I am interestid in the following cases:
- Vector bundles ($F=\mathbb{R}^n$)
- Vector bundles over spheres ($B=S^n$)
- Sphere bundles over spheres ($F=S^m$, $B=S^n$)