This is such a big potentially confusing idea that affects virtually everyone and can be simplified to a couple of sentences.
Boundaries preserve you and provide you space around your experience to be the best you can be. Boundaries are built from your inside out and give you a way to balance and center knowing what will and won’t be good for your life.
Control is external and is about you telling someone else what to do. Control is about expecting someone to be something because you need them to be. Control is about telling someone who they are and what they think and feel.
Boundaries are healthy. Control is not.
People struggle to accept both from us sometimes. Don’t doubt your boundaries. You are worthy of boundaries and setting them is a sign of your strength and ability to honor yourself.