B-Brite, and PBW. Cleansers remove surface grime and particulates. Cleansers are essential to allow sanitizers to do their job. You can't sanitize a surface if it's not clean of grime and debris, which is where cleansers come in. These products should be used on bottles, fermentors, and other equipment which has extended contact with beer. Cleansers should be rinsed after use. Don’t soak your equipment in a cleanser solution for longer than the time recommended on the packaging.
Star San, Iodophor, Saniclean, Easy Clean, IO Star, and One Step. These kill microbes and surface bacteria and make equipment safe to use with beer. Arguably the most important component of the brewing process. Without sanitizers beer would be full of other organisms that turn beer sour and undrinkable. A key feature of these sanitizers is that they're "no-rinse" so your equipment can be soaked in sanitizer and then immediately used for brewing which reduces any risk for re-contamination. A note: some sanitizers are not classified as such by the FDA (like Easy Clean and One Step), but for brewing purposes they work as well as those that are. For some reason, many include the word "clean" in the name. However, all the above mentioned products are effective sanitizers.