This is a rising stem, bolted bonnet globe valve.
This is a screwed bonnet globe valve.
This is a union bonnet globe valve.
Notice that in all cases the flow is from under the disc/seat to above the disc/seat. In all but the least expensive globe valves the disc is readily replaceable as it wears, the proverbial faucet washer. Better valves also have replaceable seats although it usually requires a special wrench to remove and replace them.
The bolted bonnet is the strongest construction although the union bonnet is often used in smaller sizes. The screwed bonnet design is the weakest and most often used in residential plumbing because of its low cost.
This is a bolted bonnet rising stem gate valve.
This is a common screwed bonnet gate valve such as one would see in residential service.
Notice that the gate valve has a straight flow through it when wide open vs. the globe valve that must make two ninety degree turns. Notice also that if the gate valve is only partially open the the "gate" is directly in the flow and subject to erosion by the passing fluid. Since the erosion of the "gate" will destroy the closely machined fit of the gate to the side-facing seats the gate valve is not a preferred choice for throttling applications. Furthermore, the gate is relatively loose in the "guides" that control its motion when the handwheel is turned and under certain circumstances it will vibrate in the flow and wear the guides.
Does that help?