CoinBase BTC valuation different than Poloniex

I was going to buy some BTC on Coinbase and checked their BTC price vs what Polo shows:

Coinbase: BTC $2,527
Poloniex : BTC $2,464

Delta: $63 or ~ 2.5%

Does this seem correct?

When I looked at Litecoin it was much closer in dollars at first look:

Coinbase: $47
Poloniex: $45.52

Delta: $1.48 but percent change is 3.1%

So if you buy on coinbase you buy in at levels below current market on Poloniex. Then have to pay a fee to purchase the coins. Then have to pay to transfer the coins…

Is there a better way or am I missing something?

Poloniex is driven my the market. There were times in the last few weeks that poloniex was only a few dollars the difference, but mostly lower than coinbase.

Isn’t Coinbase working with real fiat and poloniex working with tether, and the issues with that.