According to an English-Japanese Dictionary published in Japan,
1. She taught kids English. (implies that the kids acquired English.)
2. She taught English to kids. (does not imply whether the kids acquired English or not.)
There is no difference if the sentences are in present tense.
She teaches kids English = She teaches English to kids
Is the above true?
Using the present tense simply changes the meaning.
She teaches kids English. - That's her job or what she does regularly.
She taught kids English. - This likely means "she used to teach kids English", but no longer does. It could also mean that the duration of this action was, in a relative way, very temporary. Maybe she just taught kids English for an international exchange program, and this only lasted for a couple or a few weeks.