The word Bishop does occur in the Bible but not in that form. It evolved from the original Greek EPISKOPOS, which means literally 'Overseer'.
In English, we often shave the '-OS' inflection off Greek nouns, so we can see how EPISKOPOS became EPISKOP, before becoming BISKOP and finally BISHOP.
Paul was an Apostle and ordained both Timothy and Titus as Episkopi, but as their Overseer, he was also their Episkopos, so the distinction is a moot one because, like the offices of the so-called 'five fold ministry' it is not a strict designation of rank but a description of function. It is however, higher than a Deacon because Paul discusses both separately in 1 Timothy chapter 3.
In my hub, 'The role of the prophet in the Church', I exaplin how all five ministry gifts are complementary and intended to act together like the fingers of God's hand, to equip and not strip the saints for the work of the ministry.
An apostle is a 'sent-out-one', whose job is to establish local churches.
An evangelist is called to preach the Good News which in Greek is the 'Evangelion'.
A prophet speaks whatever he hears from God, that God wants spoken to the Church.
A pastor is appointed to shepherd God's flock.
A teacher is to impart whatever truths the Teacher (the Holy Spirit) directs.
All five overlap to varying degrees because each is God's gift to the Church, operating in the power of the Gift who is none other than the Holy Spirit himself.