gene expression is the process of transcription and translation of gene to protein. By gene control you probably mean control of gene expression. For more details look to any MolBio book

Gene Regulation may be more of Gene Control.

Gene expression is when a gene is turned on, thus it is said to be expressed. But is the expression full throttle and at maximum expression? or is it slow? is it the full length of the gene? or an alternative form? how is the transcription of the gene being controlled?

But if a gene is turned off, it is still a gene, and has not disappeared. It is being controlled someway to be turned off. Such as a repressor? epigenetic modification of the histones? or even methylated DNA, can condense the chromatin so it is not accessible to the factors needed for transcription?

And then the gene is expressed only transiently for a cell-cycle, or perhaps the gene is expressed during the M phase of the cell-cycle. How is this gene expression regulated/or controlled?