What Do These Numbers Mean?

Fuzzy is correct, the numbers are the same.

1. The position the bill was on the sheet. F6 means it was on row 6 (F) and the 6th column (6).
2. and 3. The mint it was made at.
4. I think that is the plate serial number, but not 100% sure.

Please someone correct me if I am wrong.

so if #3 and #4 on my picture are both the plate serial numbers, why are they different numbers?

Madmortician has confused the discussion.

1. The issuing Federal Reserve Bank (F6 is Atlanta).
2. Position letter and number for the face plate. See the link in Fuzzy's post. This is the fourth note down in the first column on the sheet.
3. Plate number for the face plate. This letter will always be the same as the letter in #2. The number is the plate number. The FW means this note was printed at the Fort Worth facility. Notes printed at the DC facility do not have an identifier so all you will see is the large letter and number.
4. The back plate number.

Correct.