Here are the basics:
A 'wind swell' just means that the waves are made from wind blowing over the face of the water.
(the actual verb for this is 'fetch') Fetch is wind blowing over the face of water, transfering energy from the wind to the water, creating waves.
A 'ground swell' is a swell that is produced up on the beach and moves out to the ocean. Just kidding.
A ground swell is the same thing as a wind swell, because when it comes down to it, both of them mean wind blew against the water to produce waves.
The difference is a ground swell happened far away, in other words, the wind blew against the water far away from the beach, and the wave traveled a great distance, building up energy as it traveled, to get to the beach. There is a little bit more to it, the fact that a ground swell is also characterized by low pressure slamming down onto the face of the water, but again, it is pretty much the same thing.
Typically, a ground swell is a heavy, powerful wave, whereas a wind swell is usually a wave produced by more localized weather, therefore it never really gets a chance to become super powerful, and they tend to be blown out from the wind blowing 'onshore'.
An Onshore wind is the wind blowing from the ocean ONTO the shore. Sounds like a good thing, in some cases it is, but sometimes the wind is so strong that it blows the top of the wave over, and therefore, the waves become "Blown Out" I surf a lot of heavy blown out waves, because all of the surf on the great lakes is Onshore, and usually with heavy winds, but we have jetti's and piers that block the wind and shape the waves, so on a heavy onshore wind, we get clean peeling waves. So in a way, yea it does depend on where you are at in the world and what you are trying to surf on, but mostly in the ocean, an onshore means that the wind is going to blow from behind the waves (from the ocean) and blow the top of them over.
An offshore is just the opposite, it is the wind blowing From the shore Onto the ocean. Here on the great lakes that means there is not going to be any waves, but in the ocean (during a ground swell) it means that those big heavy ground swells are going to be hit right in the face by wind, a light offshore will slow the wave down a little bit, and it will clean it up so it looks like a glassy swell, and it will prevent the waves from being blown out.
As far as Wind Speed goes, well the stronger the wind, the bigger the waves, providing that water temperature and pressure system are working together (Low Pressure against Warm Water = Good Waves)
As far as wind direction or swell direction, basically they are the same thing, except one is talking about the direction the wind is COMING from and the other is talking about the direction the swell is COMING from.
A NW wind is coming from the Northwest and blowing towards the Southeast. A N/NW wind is blowing from the north / north west, all this extra north means is that it is a lot more north than it is west.
Which is where wind angle comes into play.
Wind angle tells you what degree the wind is blowing at. Think of a compass, it is just a circle, at the top is North (which is 360 degrees OR zero degrees - truely it is called 360 degrees)
Once you move towards the East you are now at 90 degrees (everything from 360 (or zero) to 90 degrees is just between them, so if the wind is blowing at 15 degrees, it is blowing N/NE (out of the North East, but More North than east)
AND just to finish off, 180 degrees is dead south, and 270 degrees is dead west).
Usually you only use the ANGLE when you are talking about wind, it is not common to use the angle when talking about ground swells, with ground swells you just say it is a N/NW or a SW or whatever. I have only heard the ground swell referred to in degrees for precise forecasting.
So, if you are standing on the shore, in California, facing dead west (and the shore is perfectly alligned North and South)
And there is a ground swell coming from the W/NW (North West, but more west than North) and there is a 5-8 Knot Offshore, you are going to have a hell of a good time.
Tides, Basically during high tide, the tide is way up on shore so the water is a little deeper, therefore it is more unlikely that the waves will break against sandbar, during a low tide the water goes back out, so the waves break hard against the sandbar, and when you get there at High Tide and it is Moving toward Low tide, you get to paddle up down the shoreline chasing the break.
In Michigan, things are a little different, like I said all we have is onshore, super windy days but we use cement foundation piers and jetti's to block the wind, and shape waves. (just figured I would include a little about the lakes so everyone doesn't think I am crazy for talking about 40 knot winds being awsome for suring in)
AND I GET THE AWARD FOR THE LONGEST POST... Hope this helps a little.