The old but never satisfyingly answered question

[trogluddite]

Dare we conclude that cross-fading is type of morphing, or should I duck for cover?

It should only called cross-fading once the controversy has made everyone cross enough! [ducking]

...the second is a blend...

For a concise control name, I find "blend" very fitting - descriptive and suggesting something slightly more involved than a static oscillator "mix".

trog just gave the ultimate answer: a big knob labelled "morph"

If not quite as succinctly as Adam's visuals! I'm a great believer in the old saying; "1000 words is worth a picture!" (or is it the other way around?)

[MichaelBenjamin]

.

[RJHollins]

.... and of course, I hesitate the mention of:

'Dissolve'