FYI the different frequency bands are for different regulatory markets, and one should figure out which module is legal in their country before buying.
Before buying a module, I would recommend watching Andreas Spiess's youtube videos on LoRa; he has several.
The sub-GHz hardware is non-LoRa ISM-spectrum. However, again this has differences in specific subspectrum licensing. While learning about radio regulation is perhaps interesting to some people and arguably important, practically speaking this stuff is not high power so it would be hard to cause problems with it.
Before buying a module, I would recommend watching Andreas Spiess's youtube videos on LoRa; he has several.