If the circulating supply and total supply are not the same it simply means that not all the coins are currently circulating. This could be due to the project holding a portion back in some kind of escrow, or not all the coins have been mined yet, provided it’s a mineable coin. Technically the value could go down if more coins are put into circulation. In the case of Bitcoin, because there is a more limited supply than many other coins, the price will fluctuate based on usage, adoption, and speculative demand. Once all Bitcoins are mined (we just crossed the 80% threshold) then the price should find its high and generally not fluctuate as much.