The difference is mainly subjective, related to the viewpoint of the person setting the prices and the person having to pay those prices.
A lot of people think it’s gouging, for example, when a large-scale regional disaster occurs, such as a massive flood or highly destructive hurricane, which wipes out a lot of infrastructure in an area, and sellers of things such as fresh food, potable water and ice, to name a few, jack up the prices to “much higher than normal” rates. The fact of the matter is that after this disaster, those commodities that are in very short supply and difficult to replenish just got a lot more valuable because of the disaster. Expecting the supplier to hold his prices static in the face of overwhelming demand is counter to any rational expectation of economics.
In fact, if worsening shortage + higher-than-normal demand doesn’t cause prices to at least temporarily skyrocket, then the resource that is in such short supply and for which people are so desperate is more likely to be wasted or misused than otherwise.
Take ice, for example, in a summer hurricane that wipes out electricity (and therefore most refrigeration) over a wide area. That ice, because it is now more needed than usual (because no one can make their own, and because people’s refrigerators are holding food that will spoil without cooling) is now more highly valued by everyone. But for some people the need is critical; it can be a life-or-death event if blood banks aren’t kept cool or if insulin isn’t stored properly. Should that be considered the equivalent of “the people who live closest in the neighborhood and don’t want their leftovers to spoil”? I don’t think so, and that’s why I would support the retailer charging very high prices for the few bags of ice that he may have in stock, so that people who need it to save their lives would be able to find it. No one would spend $100 for a bag of ice to chill his beer, so it might be available to the guy who wants it to chill his insulin for a few days.
What @Cruiser said is apt: Prices send signals to suppliers that “here is a market that is worth your while to supply”. At an (allowed) price of $100 per bag, ice would flow to stricken areas like that – and quickly! – bringing prices into a lower equilibrium as supplies increase. It’s very fundamental economics – which very few people seem to understand, and no politicians.