I can't speak to cyclothymia personally because I'm bipolar 1, but I have a good friend who has it. She describes it as periods of mild depression and mild mood elevations that don't quite rise to the level of hypomania---she has extra energy and she is more talkative and easily amused than usual. But she doesn't spend money irresponsibly, nor does she do things like rearrange the sock drawer at 2 in the morning or pressure-wash the porch for 4 hours straight. (Yes, I've done those things.)

It's all in the degree of the "high" mood as to whether one gets diagnosed with BP and what specifier is used (BP 1, 2, or NOS).