So what is the difference between the two? I need a pair of end nippers, but not sure what to get, or what the difference is. I need it mainly for cutting nails flush.
Rebar tie wire is made from soft annealed wire, which is generally available in 18, 17, 16, 15, and 14 Gauge. Concretors nippers are made to twist and cut wire in one operation, hence the name.
End nippers are designed for carpenters to cut off nails and whatnot.
Just for the record, I've been in the construction inspection business for 25 years, I see guys tying up rebar virtually every day, and the only tool I've ever seen used for tying tie wire are the Klein Tools D201-7CST USA 9" Iron Worker Rebar Tie Wire Pliers. I asked rod-busters at various jobs about the "concretors nippers" but none had even heard of them so I carried a picture to show them at which they just laughed. This was even funnier than the electric tie-wire doohickey that the union electricians use to tie conduit to rebar to hold it in place.