Sorta the same but alot different. The size is just the same.

The LQ4 is a 6.0.

That 5.3 is a aluminum block unlike the iron block 5.3's in the trucks. Only other 5.3's on the denali envoys and trailblazers got a AL block. Kinda everything about is special, front cover, water pump, power stering stuff, flex plate, oil pan etc are all made just for being stuffed in a FWD car. In short, it's a truck motor but in a car and weights alot less but makes roughly the same power.