Rope like burn on neck from smart lipo chin 5 days post op, is it bruise or burn? (photos)

This appears to to be a bruise that has settled in your first neck crease.  However, it needs to be followed closely by your treating doctor to check for progress.  The skin is tighter in these transverse creases and frequently holds bruising in a line this way.

A burn from laser lipo will usually show up as a blister within minutes to hours of the procedure. Ischemia or pressure necrosis secondary to a compression garment that is too tight can also feel and look very similar. A bruise will usually lighten in color as time goes on, while a laser burn usually darkens, eventually turning black. If yours is improving, bruising is the likely culprit. Take care with your compression and seek your surgeon's opinion.