G5, focus following or AF-C?
Is there any difference in speed between this methods?
Using the right terminology would make your post much clearer.. but I assume you're talking about AF-C versus AF Tracking.
They're not the same.. In a nutshell :
AF-C continously focuses on a moving object.. but if some other object comes nearer, then its focus switches to the closest object.
AF tracking tries to "memorise" the moving object.. and even if some other object comes nearer, its focus should still remain locked on the "memorised" object..