I don't think Hayward went into a better situation talent wise. They are going to drop at least two key pieces to bring him in, and will still deal with additional max type contracts next year, or risk losing players. Honestly, I don't like IT, and I think he will always hold that team back.
I do think he went into a better system for his skillset, and he will make the ASG/get more hype in Boston.
Utah and Boston are kind of opposites. They have way more offensive talent than Utah, but less defensive talent (though they do have very good perimeter players who can put on heavy pressure). I wouldn't say either team was significantly more talented than the other, just different.
I thought what Utah had going for it though was they were younger and could make him the focal point. The negatives for Utah were pretty big though (injury concerns limiting upper ceiling potential, the warriors exist in the West, and Utah probably cant afford as big of a LT bill that Boston can).