What actually moves the rate you are quoted

The number you see on a swap is not the price on a chart. It is what someone will actually trade with you right now, which is a different question.

The three parts

• The market price. Where the pair is trading.
• The spread. The gap between what buyers bid and what sellers ask. Thin pairs have wide spreads, which is why an obscure asset quotes worse than a major one.
• The network cost of getting the coins to you.

Why two services differ

Different liquidity sources, different spreads, different fee handling. A service quoting far better than everyone else on an illiquid pair is usually either quoting a number it will not honour or taking the difference somewhere less visible.

What to compare

Compare the amount you will actually receive, not the headline rate. That single figure already contains the spread and the fees, which is why Swap Heaven shows it before you commit to anything.