I have never noticed any difference. Some larger varieties of winter squash take more time. But never any appreciable different among C. pepo. ( acorns versus Zucchini, Delicata versus crooknecks)

I've never noticed any difference, either -- both summer and winter squash germinate quickly IME (indoors under lights).

Thanks! Anyone else?

Age and quality of seed makes a difference. I planted some 4 year old Ferry Morse straightneck squash at the same time I planted some fresh Baker Creek Costata Romanesco seeds. The CR came up in 7 days but the straightneck took 12 or 13. Larger cucurbit seeds also seem to take a little longer than smaller ones IME.

Or you planted the winter squash a little deeper.

Lots of variables and I doubt you will get a definitive answer to your question.

I thought about deeper and generally larger seeds take longer - but I do not think that was it. Interesting that older seeds took longer.............

I've noticed that the Australian Blue winter squash (C. maxima) takes 2-3 days longer than Tromboncino (C. moschata) and the hull-less seeded pumpkin I'm growing this year (C. pepo). Since Australian Blue is the only C. maxima squash that I grow, I don't know whether the late germination is a characteristic of the species, or of the variety. Maxima squashes tend to be large seeded, which may be a factor.

Virtually all summer squash is C. pepo (with the exception of Tromboncino); winter squash can be any of the three species above.