[Alchemist]

Well I'm perhaps even more confused now than before I posted the hands. The concensus seems to be to check the first hand and bet the second. Both hands seem almost identical to me, so maybe I'm just retarded.

On 4th street I have a 4-card 8 against presumably a good 3-card low with a brick.
5th we both catch good.
6th I catch paint and him a 9.
River I pair up.

So what specifically makes the second hand a bet? Is it because 6s are no good to him? If he catches a 7 on 5th instead of the 8, does that make the river a check?