2 weeks post op Liposuction, what is the hardness in inner thighs and knees? Is this normal?

The fat removed by liposuction is in part replaced by fluid or swelling. This can feel quite firm and may take weeks before it completely Resolves

It is entirely normal to feel some firmness in the areas that were suctioned.  If your surgeon recommended a compression garment it will help some with the swelling...which is what the firmness is. The swelling is usually at it's worst that second week when you start increasing your activity.  Be patient, it will resolve.  If it is  particularly irregular I would ask your surgeon about it at your next postop visit.