"Pag-ibig" suggests a more intense level of love and when directed at people would most likely mean romantic love. "Pagmamahál" is more general in application.
You can have "pagmamahal" towards everyone you know, but it would sound improper if you'd have "pag-ibig" towards your parents, siblings, children, relatives, and friends other than that special someone in your life.
Pag-ibig Example Sentences in Tagalog: (5)
Can you feel my love for you?
It hurts to have a broken heart.
old-fashioned love songs
You will never forget your first love.
Have you already experienced failure in your love life?