The difference between big delta and small delta?

1. Jul 14, 2011

aCHCa

Could anybody explain me what's the difference between $\delta\Gamma^{\rho}_{\mu\nu}$ and $\Delta\Gamma^{\rho}_{\mu\nu}$? Thank you

2. Jul 14, 2011

Polyrhythmic

The first usually refers to a variation of the quantity, also used in linearized gravity.
The latter is just the Laplacian:

$\Delta=\partial_{\mu}\partial^{\mu}$.