How is a DNA microarray different that gel electrophoresis?

I know that they are both used to kind of sort DNA and whatnot, but what's different?How is a DNA microarray different that gel electrophoresis?
Microarrays are used to measure gene expression but Gels are used to seperate DNA fragments.How is a DNA microarray different that gel electrophoresis?
A DNA microarray (also commonly known as gene or genome chip, DNA chip, or gene array) is a collection of microscopic DNA spots, commonly representing single genes, arrayed on a solid surface by covalent attachment to a chemical matrix. DNA arrays are different from other types of microarray only in that they either measure DNA or use DNA as part of its detection system. Qualitative or quantitative measurements with DNA microarrays utilize the selective nature of DNA-DNA or DNA-RNA hybridization under high-stringency conditions and fluorophore-based detection. DNA arrays are commonly used for expression profiling, i.e., monitoring expression levels of thousands of genes simultaneously, or for comparative genomic hybridization.