Just referring to what particles the released energy is carried in.
The easiest fusion reactions to make happen release most energy as neutrons. But neutrons are, from a practical standpoint, a huge pain in the ass to deal with. They just fly off until they hit another atomic nucleus.
They irradiate the structure of reactor, making it radioactive and weakening it, neccesating periodic replacement. This means handling radioactive materials, which as the existing nuclear power industry demonstrates, is hard to make cheap.
Reactions that release excess energy as charged particles, though all harder to actually do, leave you with charged particles that can be directed by electric or magnetic fields and can be used for direct enerergy conversion.
Yes solar requires a lot of surface area, but fusion power is just not looking like it will be anywhere near cheap enough for the real estate savings to matter.