What’s the difference between the SFP module & SFP+ module?
Main diff is speed. SFP can link up to 1gbps or lower. SFP+ can link up from 1gbps to 10gbps, but can’t go under 1gbps.
SFP used to support longer distance than SFP+, but I think this isn’t like that nowadays.
Some ports support SFP and SFP+, but not always: you have to check port specs first.
SFP and SFP+ transceivers are virtually identical in size and appearance. The primary difference is that SFP+ is an updated version that supports higher speeds up to 10Gbps. The difference in data rate also accounts for a difference in transmission distance—SFP typically has a longer transmission distance. SFP+ specifications are based on SFF-8431. In terms of SFP vs SFP+ compatibility, SFP+ ports often accept SFP optics but at a reduced speed of 1Gbps. Be aware, however, that you cannot plug an SFP+ transceiver into an SFP port because SFP+ does not support speeds less than 1Gbps.
From this source: SFP vs SFP+ vs QSFP: What’s the difference?
Also a good video with simple explanation:
SFP transceivers are one of the most common transceiver form factors in the networking industry. But, what is it, and what’s the difference between SFP and SFP+ transceivers? Watch and find out!