Simplified, it's like this:
4 basic Reverse designs were used with Morgan dollars, referred to as A, B, C and D. "A" reverses are the 8 tailfeather design used in 1878 only. "B" Reverses were used, in a couple forms, for 1878 P, S and CC coins, some 1879-S and some 1880-CC coins. The "C" Reverse was used on everything else through 1904, and the "D" Reverse is 1921 only.
There are sub-variants of most of these. The ones which you're interested in are the two major "B" Reverse variants, B1 and B2. Here's the B1, known as the Long Nock:

Note the length of the center arrow shaft. Here's the B2 Reverse:

Again, note the center arrow shaft. That's what we mean by "Long Nock."
4 basic Reverse designs were used with Morgan dollars, referred to as A, B, C and D. "A" reverses are the 8 tailfeather design used in 1878 only. "B" Reverses were used, in a couple forms, for 1878 P, S and CC coins, some 1879-S and some 1880-CC coins. The "C" Reverse was used on everything else through 1904, and the "D" Reverse is 1921 only.
There are sub-variants of most of these. The ones which you're interested in are the two major "B" Reverse variants, B1 and B2. Here's the B1, known as the Long Nock:

Note the length of the center arrow shaft. Here's the B2 Reverse:

Again, note the center arrow shaft. That's what we mean by "Long Nock."



















