The present perfect tense is used to discuss actions that have started in the past but continue in the present. For example, the sentence "I have taken guitar lessons since the sixth grade" suggests that the speaker started guitar lessons in the sixth grade and still continues to take these lessons in the present time.
The present perfect continuous tense is also used for actions that started in the past and continue in the present, but the continuous tense is used for actions that are in fact continuous and taking place over the span of some time. Writers and speakers use the continuous tense to emphasize the continuity of the action. For example, the sentence "I have been running to work every morning since September" uses the continuous tense to emphasize the action of running.