In addition to the great advice offered above, the other thing is that you could be cueing the movement wrong in your head. I think the squat is far easier than the deadlift to understand to a degree that you can actually get going and begin training it, however when you get down to it it is a more technical lift, and the more you do it, the more you read about it, and the more you get critiqued on it, and the more time that passes, the better you'll get at it (just from a technique perspective). There are definitely nuances that people might miss if they only look at what you look like. For what it's worth I was at very similar numbers a little over a year and a half ago (305 max squat and 405 max deadlift, and I'm much taller). Both numbers have gone up over 100lbs, but there's still a pretty big gap in the numbers, and my weakness is my upper back which I know since my weak point on the DL is the portion past the knees and halfway up the thigh (I don't hitch it, I'm just using that as a point of reference).