will u please tell me the difference between nucleus and nucleoid.

 The word nucleus means kernel or core, and it comes from an Ancient Greek word meaning nut. As a general rule, the nucleus is so critical that the surrounding structure cannot survive without it. Nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these chromosomes are the cell's nuclear genome. The function of the nucleus is to maintain the integrity of these genes and to control the activities of the cell by regulating gene expression. the nucleus is therefore the control center of the cell.

Nucleoid is a region in the cells of prokaryotes that contains nucleic acids but which is not bounded by a membrane: it is analogous in function to the nucleus of eukaryotic cells.