It's probably a case of dramatic neccessity, but if I wanted to explain it using the suspense of disbelief, I'd say that Force lightening doesn't have the same properties as regular lightning. In particular, Dooku uses Force lightning without harm to himself. This is unlike real lightning, which would fry him. Dooku also uses it to specifically move Anakin from in front of him to his left, straight into a wall. This seems inconsistant with the properties of normal lightning. He should have flown straight back.
Also on the list is the uncharacteristic way in which it affected Mace: it shocked him like lightning would (A bit overly visible, but hey... whatever) and he wasn't smoking or anything or catching fire... then of course he suddenly shoots back (Which is either a Force push on the behalf of Sidious or it implies that Force lightning acts more like a painful tractor beam than anything else).
And then if you look at the way it gathered in Yoda's hand on both occassions and how it caused the explosion... again, not exactly consistant with just a stream of electricity. If it had been an electric-related explosion on that pod in ROTS, the thing would have been scortched and Yoda and Sidious missing some eyebrows.