Guru: an influential teacher or popular expert
My definition of guru is based on the above meaning, not the Hindi spiritual teacher
From my perspective of understanding who is a guru and teacher in a real-life experience, a guru is a man full of knowledge in his field or many fields and can be a critical thinker. They can be fooled by their understanding, they can be impatient, full of pride, selfish and also not a good instructor. But a teacher is someone who studies to impact others morally, educationally and spiritually.
A guru is made through a teacher who instructs him/her on what to do and how to do it which makes them a foundation of knowledge, wisdom and rebirth of knowledge.
Spiritual Gifts and Talents
Spiritual gifts are given by the Holy Spirit to edify one body of Christ Jesus and to ensure we spread the good news of our Lord to the world. These gifts can fade away if we misuse them and God can wish to allow you with the gift even when your heart is not in the things you do with the spiritual gifts because at the end every human shall give an account for his or her deeds. We have gifts of teaching, healing, prophecy, discernment, tongues and etcetera but all served one purpose. Teachers of the Holy Spirit can teach spiritual matters as God reveal to them to observe and tell others. Talents are given by God as an inborn gift that men used also to serve God. Every child is born with a talent but a spiritual gift comes only when we proclaim Jesus is Lord over our lives and welcome the Holy Spirit to dwell in us.
Eventually, a guru can pick up a Bible and teach you all things and quote Bible verses offhand but without spiritual impact but a teacher could just speak a verse and your soul shall find rest.
"Every wise instruction is a teacher"
Apostle Sam Diko