I am new to bitcoin and crypto in general.

I have decided to try to look through as many as the resources out there that I can and I have start noticing some strange things. For example, bitcoinwatch.com has the current value of BTC/USD at $597 where yobit.net has the value at $621. Which is more accurate? Can one be more accurate than the other? Are both values accurate but, the two sites just have it at different values?

And is there a site better than both of these that I may have overlooked?