Hooks can vary from Manufacture to Manufacture. An Eagle Claw Hook will be slightly different in Size than a Mustad, VMC, Matzuo, or a Gamakatsu and Visa Versa. What remains the same is the size chart. Below you will see a size chart that will explain the mystery, for example, between a #2 Hook and a 2/0 hook. There is a hugh difference. The more you go to the Left the smaller the Hook. As you go higher on the chart the Hook Gets Larger.
#12, #10, #8, #6, #4, #2, #1, 1/0, 2/0, 3/0, 4/0, 5/0, 6/0, 7/0, 8/0
The smaller hooks are used for smaller fish like, Brook Trout, Bluegill, Perch, Crappie #12, #10, #8, #6, #4, #2
The most popular size is the #4 hook
The larger hooks are used for Larger Fish, Bass, Walleye, Northern Pike, Musky
The most popular size for Bass is 1/0, 2/0, 3/0, 4/0, 5/0
The larger hooks are popular for Musky and Saltwater Fish 6/0, 7/0 and 8/0