When I first got into crypto, I couldn't figure this out either.
A trading pair like ETH/BTC is quoted in BTC, so it shows how ETH is performing relative to BTC. That's different from ETH's price in dollars.
Trading activity varies across pairs. When you buy or sell a coin on a more active pair, price discrepancies are usually smaller.
By the way: $BTC is quoted at 81158.84, down 0.53% over 24 hours.
If anything wasn't clear, ask in the comments.