How come the amount received from DEX is lower Than CEX even before the fee kicks in?

I tried to compare the amout of USDT received when trading ETH from couple of CEX to DEX, the amount received from CEX is consistently higher than DEX even before fee kicked in(I tested quantity amount of times with each test within half second to migated market raise/drop). For example when trading 1 ETH in multiple CEX, the amount received is about 3368-3372 USDT, but consistently receive 25 or more USDT less if tested in DEX around 3343-3347 USDT even before fee kicks in, the amount receive after fee is even lesser around 3314 USDT By the way, why exchange in Exodus is ridiculously expensive even compare to other DEX? submitted by /u/Starforce2005 [link] [comments]
http://dlvr.it/Rz3Q64