(Q&A) What are the differences between preaching (பிரசங்கம்) teaching (உபதேசம்)?

Question (16-Jan-17): 

What are the differences between preaching (பிரசங்கம்) teaching (உபதேசம்)?

Is there any guideline; who can preach and who can teach? Or anyone can teach (உபதேசம்)...

A complicate question which requires to be understood specifically.
உபதேசம் refers to Teaching (one who teaches what is preached)
போதகம் refers to the core or doctrinal speech from the initiator which refers to our Lord Jesus Christ

Preaching lays the foundation for teaching.
However, when we look at English vocabularies, Teaching and Preaching is widely said in many cases.

The following are few quotes for better clarify:
The Great Commission in Matthew requires that we “make disciples,” Mark declares that we are to “preach the gospel” (Matthew 28:19-20; Mark 16:15).

We are to be “teaching them all things whatsoever I have commanded you.”

Paul’s work in Rome is described as “preaching the kingdom of God and teaching the things which concern the Lord Jesus Christ” (Acts 28:31).

Paul used these concepts of preaching and teaching when he said, “Him we preach, warning every man and teaching every man in all wisdom, that we may present every man perfect in Christ Jesus” (Colossians 1:28).

Sometimes, interchangeably interprets about the practice of teaching and preaching.
Matthew 4:23 declares that Jesus was “teaching in the synagogues;”
Mark and Luke indicate that he was “preaching” (Mark 1:39, Luke 4:44).

In Jerusalem, the same apostles who were “proclaiming in Jesus the resurrection from the dead” were at the same time “teaching the people” (Acts 4:2).  While the term preaching refers to the message announced, the term teaching may have people as its object.

We read Teaching and preaching the word of the Lord” at Antioch (Acts 15:35). 
In any case, preaching and teaching go together.

In short, we as God’s spokesmen, teach what is preached.