Is there a difference between sunblock and sunscreen?

Not anymore.: In the past the two were used interchangeably... But sometimes they weren't... Block should be better than screen, right? Confusing, huh? Well to clear up confusion, the fda recently (6/11) banned the use of the term 'sunblock' and the ban will be enacted in a year. So it's just sunscreen now.

Nope: Sunscreens work via 2 possible ways: 1) chemical blocks that breakdown the uv rays as they pass through the skin and 2) physical blocks that prevent the uv rays from getting to the skin. I recommend the physical blocks (zinc and titanium) because they have a very good safety profile and work very effectively. If you are going to be in the sun - use a minimum of SPF 15 - follow product directions.

Many: Sunblocks contain ingredients that reflect the uv rays to prevent damage whereas sunscreens contain chemicals which absorb the uv energy, thus lessening damage. Typically blocks are opaque and screens transparent but that is not always true and the differences are further complicated because manufacturers often mix chemicals/mislabel. Blocks tend to protect more and be less irritating.

Shield vs filter: True sunblocks essentially create a shield to effectively block out the sun with zinc oxide being one of the most common preparations. They tend to be opaque. Sunscreens are chemical agents which filter out undersireable wavelengths of the sun and come in a variety of strengths and formulations. They tend to be clear. The diagram represents the spectrum of coverage.