Section 167 CrPC: Is Investigation at Police Station a Custody?

Yeh Section 167 CrPC ka toh pura jhundhla hai. Investigation at police station kya hai, police custody kya hai, dono kaa difference kya hai, usne kaha hai ki investigation police station mein hone ke baad bhi, accused ka police custody mein bhi detention ho sakta hai. Ab maine suna hai ki yeh Section 167 ka vishesh prakaar hai, lekin ye kyu? Investigation police station mein hone ke baad bhi, court ko aazma hai ki usko detention karna chaahiye ya nahin? Agar haan, toh yeh police custody nahi hai, tab to yeh kyu Section 167 mein likha hai? Yeh toh confusion hi confusion hai, aur kya hai koi logical explanation?