What is the difference between 208V vs 240V single phase ?

[Carultch]

Much of our industry does refer to residential services as being single phase even though the voltage is 208 L-L and 120 L-N.
Some people refer to this as an open-wye service.

I like the term "open wye service". Alternatively, I might call it a "partial wye service". It seems much more descriptive of what really is happening. The industry norm of calling it "single phase" in my opinion, is a bit misleading. Because I see it comes from 2 phases of the original grid, and needs 2-pole breakers, so it begs the question when first introduced, "what exactly is 'single' about it?". (I now know the answer, so no need to respond).