TDP = THERMAL Design Power
This relates to the amount of cooling necessary for the GPU. The RX 480 GPU is only pulling about 110W, so it is pulling less than the TDP.
TBP, however, is not commonly discussed - but most treat TDP as if it were TBP (typical board power).
RAM has a significant impact on power consumption. I'd love to see some RAM underclocking tests on the RX 480 - as I underclock my own RAM on my R9 290 to save oodles of power.