I do use them interchangeably. The New Testament often portrays those two Persons of the Trinity as sharing the same essence. Jesus said he and the Father were one. When Thomas called him God, Jesus didn't correct him. He said that his words and work and the Father's words and work were one and the same.

Jesus and the Father were two of the three Persons of the Trinity. I think it was Augustine who said the Trinity distinguishes between the principle of divine action and the subject of divine action. The principle of all divine action is the one undivided divine essence, but the subject of divine action is either Father, Son, or Holy Spirit. The Father can send the Son according to his power, and the Son can be incarnated according to his nature without dividing the divine essence.

I use the two interchangeably sometimes, but sometimes I also distinguish between Father and Son, depending on what I'm talking about.

I've noticed in some media that people use Jesus Christ to mean the same as God. The term Gadzook's meaning God's Hooks, but its in reference to the nails in Jesus at the crucifix is one use of the top of my head.

Is this common, or do you strictly refer to Jesus as the son of God?