What's the difference between MDO and MDF?

I’ve seen you use MDF in projects and jigs many times in WOOD® magazine. Then I heard on a TV remodeling show about something called MDO. What’s that?

Differences between wooden boards: MFC, MDF, HDF and Plywood - IVAN HARDWARE

Log lessons you can use at the lumberyard

Industrial MDO Plywood G2S 3/4 X 4x8 DSI Woodworking, 52% OFF

What Is MDO Plywood? - Curtis Lumber & Plywood

MDO Medium Density Overlay Signboard

What's the difference between rotary-cut and bookmatched plywood veneer?

MDF goes on a diet

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What is the difference between plywood and MDF? - Quora