Allen Screw?

Exactly. The only reason I knew the terms were interchangeable was because I’ve built engines on some British cars. To be fair- usually the screw is referred to as “grub” when it holds something in place with an index, as in, not all Allen/hex screws are grub screws... but that is only in the world I’ve lived in. Some people call all hex screws grub screws. 
 
Call em grub screws in Australia. But we do speak English here,like they do in England.:)
And they don't necessarily need to be Hex or Allen head.But it is easier to work with.
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