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).
the procrastinating wine maker in the Niagara Region of Ontario Canada
"Visual signs of fermentation are highly overrated"