Vision: It communicates truth about God's actions, purposes, or future events. It is the mode of revelation. It is a divinely given perceptual experience in which God communicates truth by presenting images, scenes, or events to a prophet or seer.
A symbolic vision (and Revelation, portions of Ez and Dan is a book of symbolic visions) is a vision in which the thigs seen are not the realities themselves, but representations that stand for other realities.
The form is visual and concrete (beasts, horns lamps, cities, horses, keys, swords etc. What it refers to is often abstract, historical, spiritual or future (kingdoms, powers, judgments, covenant realities). The objects are signs of something beyond themselves. IOW the image signifies the thing.
Symbolic does not mean "less real" it means the truth is conveyed indirectly through representation.