Yes, both sentences have the same meaning and can be used interchangeably. Both sentences mean that something is not as good or impressive as it has been claimed or believed to be.
In the first sentence, "It isn't all it's made out to be" means that the thing being referred to is not as great or impressive as people have made it seem.
In the second sentence, "It isn't all it's cracked up to be" means that the thing being referred to is not as good or impressive as it was believed or expected to be.
Similarly, in the context of relationships, both sentences mean that the relationship is not as good or strong as it was believed or expected to be.