  We first elaborate on the theory of relative internality in stable theories,
focusing on the notion of uniform relative internality (called collapse of the
groupoid in an earlier work of the second author), and relating it to
orthogonality, triviality of fibrations, the strong canonical base property,
differential Galois theory, and GAGA.
  We prove that $\mathrm{DCF}_0$ does not have the strong canonical base
property, correcting an earlier proof. We also prove that the theory
$\mathrm{CCM}$ of compact complex manifolds does not have the strong CBP, and
initiate a study of the definable Galois theory of projective bundles. In the
rest of the paper we study definable fibrations in $\mathrm{DCF}_0$, where the
general fibre is internal to the constants, including differential tangent
bundles, and geometric linearizations. We obtain new examples of higher rank
types orthogonal to the constants.
