Kansas-Nebraska Act v. Missouri Compromise

Kansas-Nebraska Act

• Proposed to help decide whether any new state added to the Union would be free or slave
• Proposed that the Kansas-Nebraska area e divided into two parts (Kansas and Nebraska)
• Used popular sovereignty as its tool for deciding whether the state was going to be free or slave

Missouri Compromise

• Designed by Henry Clay
• Proposed that new land west of known and settled territory would be divided by an imaginary line parallel to the equator
• North of 36°30′ would be free states, while South of that line would be slave states

In my opinion, neither of the two bills were good: both accommodated slavery. The Kansas-Nebraska Act gave the right to decide to the people, while the Missouri Compromise set strict boundaries where basically no questions were asked about the rules. However, the Kansas-Nebraska Act caused a lot of bloodshed and violence to occur because people are stupid and kill each other when they don't agree politically. So, in conclusion, the Missouri Compromise was the better deal, though is was proved unconstitutional after is was superseded.

I have some further thoughts on this topic.
Why, if the Missouri Compromise was unconstitutional because the states couldn't legally declare themselves free or slave because of the Fifth Amendment, would the Kansas-Nebraska Act have been legal? It violated the same "property" rights that the Missouri Compromise did. What's the difference legally?