There is no entertainment on the 319 vs overhead/inseat entertainment on the 738. There is also 1 fewer row of F compared to the 738 (319: 12F, 738 16F).
IF in Y the bulkhead on the 319 is a curtain giving great legroom if you can snag the seat, the 738 bulkhead is cramped.
The 319 is a little bit wider overall which makes it feel a little less cramped.
Except for lack of IFE, I much prefer the 319... The seats seem wider in Y. The 738 seems a bit more cramped.