We tend to use present perfect to focus on the results of the action. I have played music for 12 years and I have learnt a lot of new tunes. Present perfect continuous is used more to focus on the doing of the action. I have been playing music for 12 years, and I’m getting better at it. Present perfect doesn’t always mean the action is continuing by the way, whereas continuous does! For example, I have written you an answer = present perfect, but I’m stating something I’ve done and stopped doing, not something I’m still doing. Or you’d not be able to read the answer if I hadn’t finished it and submitted it!

The meanings are exactly the same, but the emphasis is different. To see this difference, let's concentrate our attention on the most important part of the sentence: the subject and the main verb: 1. I have played 2. I have been "Played" and "been" are both past participles but they speak of entirely different things. "I have played" tells of a playing experience you have. "I have been" only speaks of your experience of being. #1 concentrates on what you were doing. #2 concentrates on you yourself. In #2, "playing music for 12 years" is a descriptive phrase, a secondary phrase, that describes your being. It could be among a list of other descriptive terms: "I have been playing music, happy, studious, ambitious, living in Colorado, and working hard for 12 years." The sentence is about your being, and all the other terms just describe that being. I hope this helps. It is not a grammar book explanation, but I personally find the descriptions of tenses found in grammar books to be close to useless. They always leave me scratching my head and asking "What???"

Consider these examples: She plays the piano. (general truth) She has played the piano since 2015. (starting time given) She has played the piano for many years. (duration given) She has been playing the piano since/for …. (stylistic choice for vividness) She is playing the piano to entertain her guests. (activity started but not finished) She has been playing the piano since noon. (starting time given) She has been playing the piano for 30 minutes. (duration given) Sometimes, native speakers use the -ing form for stylistic reasons. For more information, consult a basic grammar textbook such as English Grammar in Use (Units 4, 9-10).

You're right that both sentences describe actions that started in the past and continue. Here's the difference: 1. Present Perfect ("I have played"): * Focuses on the completed action over a period of time, or the fact that you’ve played music for 12 years. * Example: "I have played music for 12 years" emphasizes that you have the experience of playing for 12 years. 2. Present Perfect Continuous ("I have been playing"): * Focuses on the ongoing activity or process of playing music, suggesting it’s still happening right now. * Example: "I have been playing music for 12 years" emphasizes that you are still actively playing music. In short: * Use present perfect to highlight the duration or experience. * Use present perfect continuous to emphasize the ongoing nature of the action.