is there any difference between diffuse texture which used in diffuse lighting and ambient occlusion map, or this is the same texture just different naming, because i see it mostly it looked the same?
The diffuse texture is the colour of the object without light effects. The ambient occlusion texture is a map that shows the shadows on an object if it was evenly lid from all sides (basically it tells us how much a factor ambient light should be on each position). You can also do ambient occlusion real-time, but that's more expensive.
Sometimes the diffuse texture and ambient texture are combined in one texture.
Yes. A "diffuse texture" is generally just a flat, plain color map. It's one of the oldest kinds of texture map still in widespread use today. An ambient occlusion texture map takes into account local effects of light sources (and is usually just comprised of magnitudes, not actual colors).
The Wikipedia page on AO has an image that illustrates the difference visually.