¿Cuál es la diferencia entre She saw me play baseball y She saw me playing baseball ?Puedes dar oraciones como ejemplo.

There is a small difference in meaning when a verb of perception is followed by the simple form of the verb, and when it is followed by the -ing form, as in these sentences:

(a)

Before we realized it, we saw a deer run across the road just in front of our car. Thankfully, he got to the other side safely, because we could not have avoided hitting him.

(b)

Before we realized it, we saw a deer running across the road, right in front of us. We put on our brakes quickly and just missed hitting him by an inch, as he leapt quickly out of the path of the car.

Sentence (a) describes a completed action; the observer saw the entire action of the deer's running across the road. Sentence (b) describes an incomplete action; the deer was in the middle of running across the road when we saw him. This sentence could be paraphrased to read: ".we saw a deer while he was running across the road."

The simple form of the verb, after a verb of perception, gives the idea that the action was observed from beginning to end during the time of perception, as in sentence (a) above and sentence (c) below.

The -ing form of the verb, after a verb of perception, gives the idea that the action is in progress but not completed at the time of perception, as in sentence (b) above and sentence (d) below: