What are metallic or interstitial hydrides? How do they differ from molecular hydrides?

Explanation

Metallic /intrestitial hudrides are fromed by many d-Bolck and f-Block element. These hydrides conduct heat and electricity
Unlike saline hydride, they are almost always non-stoichiomertic, being deficient in hydrogen e..g, `LaH_(2.87)`, `YbH_(2.55)`, `TiH_(1.5 - 1.8)`, `ZrH_(1.3 -1.75)` `VH_(0.56)`, `NiH_(0.6 - 0.8)`, `PdH_(0.6-0.8)` etc . In such hydrides, the law of constant composition does not hold good.
Comparsioin between molecular and mettallic hudrides.