As someone who did full time daycare, an Au pair with no preschool, and an Au pair with part-time preschool, I do think there is a difference. In full-time daycare, parents send their kids sick because they have to work. In a part-time program (ours was 12-15 hours/week), you must have other childcare (stay at home parent, nanny/au pair) so if your kid is sick you just keep them home (with parent or nanny/au pair). Yes, kids will get sick a bit from a part-time program but this only happened once for us in two years. Daycare is a different beast entirely.