It seems really difficult to tell the difference between the Eastern Toe Biter and the Giant Water bug...the only thing I found as some kind of difference was that the giant water bug has a groove in the upper front leg/arm...any more definitive info would be appreciated.

I assumed you had identified this one prior to posting the images, because you applied a name on them. Please don´t do that, unless you are sure of it.
Detailed information, and more characters to tell apart the 2 spp. are found on the species info pages.
To me it seems, that rather L.americanus than L.griseus would apply here. You agree?
Perhaps it is the best to move them to the genus level, and let someone else decide.

I can be certain it is not L. griseus as it does not have "fur" on the upper femur. It most definitely has a well defined groove instead. The shape of the head does seem, to me, to match the description. I would put it in Eastern Toe Biter, but I am only a home-made entomologist...