Excellent question isw. I screwed up some of the bottles in my very first batch of wine because I didn't understand the difference between these two.
1. The white powder is Na-meta or sodium metabisulfite. You may wish to switch to K-meta or potassium metabisulfite. It is more popular and more expensive, but actually makes little difference in home winemaking use. It is a contact sanitizer, ie contact with whatever you're sanitizing for 30 seconds or more should do the job. But it is NOT a cleaner.
2. The pink chlorinated powder is Diversol, and goes by many trade names. It requires soaking to be an effective sanitizer. Some folks say as little as 5 minutes, but most say 20 minutes or more. I was originally told 30 minutes. It is also a very effective cleaner. Personally I sometimes use it as a cleaner, but not as a sanitizer. It is very popular with beer makers because it is a stronger sanitizer than K-meta. I know of beer makers who soak their bottles in pink powder overnight as both a cleaner & sanitizer. Make sure to rinse well afterwards.
3. Personally I use an iodine based sanitizer called Iodophor. It's stonger than K-meta, is a contact sanitizer, and has a pleasant aroma. Also, not a cleaner.
How did I screw up? I used the pink powder as a contact sanitizer. Did not soak the bottles. Result? Some bottles went bad after aging a while. They literally stunk when opened. Others were just fine (perhaps they soaked long enough).