CrPC 82 vs. 83: Kya Fark Hai Bhai?

Yaar samajh nahi aaya, main to law school mein padh raha hoon aur mujhe yeh concepts itne confusing lag rahe hain. CrPC 82 and 83, dono mein 'investigation' ka mention hai, but difference kya hai? CrPC 82 ke under, police ko arrest karne ke lie investigation ka right diya gaya hai, lekin woh investigation hi kar sakte hain jab unhe arrest ke reason ke bare mein sufficient ground pata lagta hai. Lekin CrPC 83 ke under, police ko ek general power di gayi hai investigation ki, jisse woh kisi bhi case mein investigate kar sakte hain. Jab tum log mock tests dete ho, I'm at my shift, please help.