Yeah, I know - but they are both related to the OSR movement, even inspiring it. I see it as important to note with even a sparse timeline, for context and roots.
Castles & Crusade more so than Hackmaster 4e which was its own thing.
Discontent over C&C directly led to OSRIC and Basic Fantasy.
Keep in mind that the OSR is just as much about DiYers as it is about classic editions. Which is why OSRIC and Basic Fantasy mark the beginning as the "hack"* they used with the D20 SRD was so straightforward that it opened the floodgate to not only clones but various types of supplement products. It also helped that neither were not issued a cease & desist by Wizards of the Coast. Not that it would have stopped either OSRIC and Basic Fantasy but a C&D would have had a chilling effect.
I know folks like the rope in RPGs with old school spirit even if they are not targeted at one of the classic edition. I don't have an issue with that but the core of makes the OSR what it is the DiY attitude. So those things that effect the OSR the most are those things that helps move that along either by contributing content or serving as a guide for how to achieve similar projects.
*If you take the D20 SRD and omit the newer mechanics and additions what left is a hop and a skip from various classic editions of D&D.