Mary received praise and gives praise to God.
God does praise humans (eg Job, Mary). In this case, praise does not mean worship; it is an acknowledgement of positive qualities and an expression of gratitude. We should seek praise from God, not other people.
Praise can lead to some becoming proud/self-centered. Mary shows us how to handle praise in a healthy way; she graciously accepts and then praises God. In this context, praise is worship.
Mary's praise/worship was not just in words, she did it from the depths of her soul. God was great in her mind and her love overflowed. She was humble and in awe of how blessed she was. Her song of praise was very personal. She describes God in specifics; she knows His character. The language she uses reflects her knowledge of the scriptures. Despite being a teenager, she kept the Word close to her.
Mary respects and loves the name of God. God's holiness can be intimidating and it would be hard to worship Him unless He has touched your life - His mercy allows us to be in His presence.
