Hey there, SSOCC coils are made out of Stainless Steel and Organic Cotton. SSOCC:s heat up faster than regular OCC coils due to the coil material inside the coilhead (stainless steel).
Clapton coils have way more surface area due to the construction of the wire inside the coilhead, which translates roughly to better flavor and larger clouds. I haven't used my Subtank in quite a while now, so I don't have any personal knowledge on the different coilheads, but I have used both Stainless Steel wire and Clapton wire in my rebuildable tanks and drippers.
Which one to pick?
If you want warm vape and large-ish clouds: Go for the SSOCC Stainless Steel coils.
If you want better flavor and cooler vape: Go for the Clapton Coilheads.
Hope this helps you out even the slightest bit