It's just a lot of acronyms that are very confusing. Kinda like 802.11g, a, n, ac, ax. They should really rename them.QSFP+ and SFP+ are different standards.
Because the SFP and QSFP form factors are common place in data centers newer data rates have piggybacked on these two for newer standards when possible.
SFP (1G); SFP+ (10G); SFP28 (25G, 'cuz it maxes out at 28Gbps)
QSFP (4 x 1G); QSFP+ (4 x 10G; 40G [+56G for Mellanox]); QSFP28 (100G; 4 x 28G)
They're backward compatible. For example, QSFP28 to SFP28 breakouts should (ours at work does) support 40G to 4 x 10G. But QSFP+/SFP+ most likely will not support 100G/25G/4 X 25G.