Rec: usually single tank, dives in waters less than 40m (30m being max), within no-decompression limit, usually requires no safety stop, or a 3-minute stop at 5m, breathes normal air or recreational Nitrox (anything less than 40% O2), sees Nemo most of the time, usually models with fish and stuff.
Tech: usually twin tanks and/or more tanks, use CCR/MGBA, mixed gas breathing sometimes involved, uses Nitrox (usually 50% O2 to 100%) for decompression, usually requires decompression stops, 40m or deeper, diving in actual and virtual overhead environments, different gear set-up and configurations, equipment redundancy counts, dives not to see Nemo. Look cool in pictures. ;D
