It is wonderful.
The only difference is actually the material.
It is possible to veneer (cover the whole front surface) of a tooth with composite bonding
material. However, it will not be as strong as a porcelain veneer covers, and will not hold a stable color. The composite materials are more porous and will stain quicker.
The porcelain veneers
are much stronger and hold the shape and color for a much longer period of time. However, they are actually put into place with essentially the same composite bonding material and over time, the "edges" of the veneers will discolor and can leak and de-bond, requiring the replacement of the veneers.
The best was to make a change, if the teeth are in good shape and position and the only thing you desire is a color change, is a good cleaning and high power, in office bleaching (chemically, or light activated bleach will give you excellent results).
If you are looking to also change the shape of your teeth, then porcelain veneers will give you the longest lasting, best looking result. They will also cost you far more than bonding.
You should talk to your dentist about the benefits and contra-indications of the procedures before you commit to any work.
Best of luck,
dr. Zev kaufman.