There are as many different types of benches as there are woodworkers. There is a good reason for that in that each person has a different method of working, a different sense function, a different sense of cleanliness, and different tools. What's the difference between a workbench and an assembly table, in a word, a vise. Here again vises come in all types and sizes from shop built to twin screw versions costing several hundred dollars.
The problem is when you start out, you don't know enough about what methods you will use and how to secure the work safely. Having a bench that won't move around is very important regardless of the type. You can't drill or plane on a moving workpiece. The bench must have enough of it's own mass and weight to resist sideways forces OR it should be attached to the floor or the wall. Free standing benches are usually very stout and have enough of their own weight or shelves or drawers to place additional tools adding more weight.
What makes a strong, sturdy bench? It's all about how you join the legs to the top and bracing. If the only resistance to sideways forces is in the leg joints, you will need very large and thick pieces and you should use half laps, mortise and tenon or other self reinforcing joints. The example I always use is a simple cardboard box with all the flaps folding inward. It will collapse in a heartbeat. Then if you fold out the bottom flaps and tape them, it becomes much more rigid. Then if you fold out the top flaps and tape them you will have quite a strong and rigid unit. Why is that? Because the bottom and top have become braces. A workbench really couldn't have all the side enclosed, it would be a waste of space. So only the sides and back are enclosed.
The two basic ways to build a bench are:
1. Build a cabinet out of plywood and put a thick top on it for attaching the vise.
2. Build a frame out of 2 x 4 or 6's or other heavy members, and put a thick top on it. A hybrid version would have the sides and back enclosed with plywood to further reinforce it.
The top can be a solid core door, which I use also for my assembly tables, or a glue up made from 2" thick construction lumber or hardwood. Construction lumber will only be 1 1/2" thick after planing and sanding. Another type of top uses a torsion box construction. This makes for a flat and very rigid top, BUT not thick enough to mount a vise. This can be remedied in various ways.
I would look on line and buy or borrow books on the various bences before I jump in a build one.
If you enter 'workbench' in our search bar, here's what you get... several hundred threads: