The deck
A plastic board is molded in one piece: shape, kicks and whatever concave it has are all set at the factory and identical across every unit. A wooden deck is pressed from plies in a mold, and the concave and kick angles are the reason riders get picky about brands. Deeper concave gives your fingers something to sit against, which is most of what people mean when they say a deck "feels controllable." You can't add that to plastic.
Most riders end up somewhere in the 32–34 mm range on wood, with wider decks generally feeling more stable under the fingers and narrower ones flicking faster. A plastic board doesn't give you that choice.
The grip
Stock plastic boards come with a printed or lightly textured top rather than foam or riptape. Grip is the single biggest change most people notice when they move to wood, because flip tricks stop being luck. If you want to test this cheaply, tape is the one upgrade worth putting on a plastic deck — it tells you how much of your frustration was the board.
Trucks and bushings
This is the gap that's hardest to close. Stock plastic trucks are typically fixed or barely adjustable; wooden-setup trucks come apart, take different bushings and let you set how loose the board turns and how the hanger sits for grinds. Tuning is a skill, and you can't practice it on hardware that doesn't adjust.
Wheels
Hard plastic wheels against a table or a painted ramp behave differently from urethane, and riders consistently describe the stock ones as loud and skittish. Urethane — bearing or non-bearing, both have followers — rolls quieter and holds a line through a transition. Bearing wheels roll further and cost more; non-bearing wheels are simpler and plenty of good riders stay on them.
Durability and cost
Plastic is cheap and basically survives being dropped. Wood chips at the kicks, and bottom graphics wear from slides and grinds on ledges and rails, while primos wear the side edges. That wear is normal and it's part of why people keep spare decks. Whether the price difference is worth it depends less on skill level than on how much you're riding: a board you use every day earns its cost quickly.