Hiragana is a phonetic alphabet, like the English alphabet. Kanji represent meanings and have 2+ ways to pronounce each one. This is kind of a hard question to answer, because they're completely different. Japanese writing consists of a mixture of 3 writing methods, Hiragana, Katakana, and Kanji. If you want to read in Japanese, you need to learn all three. Hiragana is always learned first, and is moderately easy. Kanji take years to learn. I currently know 550~ kanji and am not even halfway to my goal of 2000. Your question is really broad, but i hope I've helped. I'd recommend you find some structure for your learning, as any textbook and most online resources would tell you to start with hiragana and would explain it all much better than me. Also you can google/wikipedia the three writing methods for tons more information. Good luck with your studies!

Definitely master hiragana! Most Japanese text books will start out the first two chapters or so teaching hiragana and katakana (used for ~mostly~ foreign words). These are easy enough to learn. As you learn kanji, most texts will write the hiragana pronunciation above the kanji, called furigana. Furigana also appears in native material for more difficult/not as well known kanji. The textbook that I used starting out is the Genki textbooks. Genki I would be my recommendation. If you learn Japanese in English, it will also help your English skills! Please message me if you have any more questions.