What's the difference between devices like the homeoblock or dna appliance and regular palate expanders? is one preferred in adults over another?

2d vs 3d affect: Regular palatal expanders r basically 2d while the other 2 are 3 dimensional and create a more stable outcome and make the regular braces treatment faster and easier. The DNA one does not alter your genes although they want you to believe it.

Surgery: You CANNOT widen upper jaw in an adult who's sutures have fused without doing surgery. You can push teeth outward, but often at the detriment to the tooth-supporting bone. PLEASE seek consultation with qualified Orthodontic Specialist. Avoid quick-fixes and snake oil. Remember, of it sounds too good to be true...