The difference is subtle to an ESL student, but very important to a native speaker, so I’d suggest you master it ASAP, which will save you the trouble of having to re-learn the pronunciation of thousands of words later. The best thing is to listen, but here’s a quick description: [ɪ] is a lax vowel, so your mouth muscles should be fairly relaxed, with your lips and tongue in a somewhat more “neutral” position than for [i]. The timbre is between that of [i] and [e], but the mouth is much more relaxed. [i] is a tense vowel, so you use your mouth muscles — really smile with your lips, and move your tongue into the front of your mouth in a fairly high position, as if to say the consonant “y” — for example “year.” In the US especially, this vowel is pronounced as a diphthong [ɪi] (accent the first part — the sound is between [ii] and [ei]. Even though it’s a diphthong, the time to pronounce it is about the same as for the monophthong [ɪ]. I hope this helps. If you’re still confused, someone else may have additional tips, if not, feel free to write me for clarification.

Why is not a good question in learning English! Just assume the answer is 'Because it is'!

Sorry, It should be "Are [ɪ] and [i] the same?"