Dreams are received whilst a person is asleep while visions are received when a person is fully awake. Dreams can be random and can vary from a person’s last thought to a glimpse into their imaginary future. However, God sometimes communicates to a man in dreams like in the case of Abimelek, Genesis 20:3
A vision is a supernatural manifestation in which a person hears or sees glimpses into the future or the spiritual; Acts 16: 9. Vision is a peek into the spiritual and can be induced by drunkenness in the Holy Spirit.; Acts 10: 9- 16. Unlike dreams, visions are never meaningless.
According to Acts 2:18, dreams are for the Old Testament while visions are for the New Testament. Revelations from God on a specific subject matter can come in dreams or visions. But it is profitable for your spirit to be attuned to God’s frequency at all times so He does not need to wait for you to be asleep before He can reveal things to you.