What is the main difference between transconjunctival blepharoplasty and lower blepharoplasty?

There are two major differences: the location of the incision and the goal of the procedure.  Generally speaking, a transconjunctival approach utilizes an incision on the conjunctiva (the inner lining of the eyelid) and is used to remove/re-position excess orbital fat.  It can also be utilized, depending on the surgeon, to perform a cheek lift.  A subciliary approach utilizes an incision trough the skin, and then a secondary incision through the orbicularis oculi muscle at a lower level.  This approach can be utilized to remove/re-position orbital fat, re-position the cheek, and remove a small amount of skin.  Either approach can be used by a skilled Surgeon, but the decision to use one approach over another is usually based on the age and anatomy of the patient.  As with other surgical procedures, the critical factor is the skill and experience of the Surgeon, not the approach. 

Transconjunctival lower blepharoplasty diminishes the fat pads in the lower eyelids and does not treat the skin. At the same time, laser resurfacing can be performed to smooth out the lower eyelid skin. A lower blepharoplasty can deal with excessive skin fat in the lower eyelids. With this procedure, there is an incision under the lash line and laterally in the corner of the eyelid.