基因间隔区：An Intergenic region (IGR) is a stretch of DNA sequences located between genes. Intergenic regions are a subset of Noncoding DNA. Occasionally some intergenic DNA acts to control genes nearby, but most of it has no currently known function. It is one of the DNA sequences sometimes referred to as junk DNA, though it is only one phenomenon labeled such and in scientific studies today, the term is less used. Recently DNA fragments in intergenic regions were known as "dark matter" or "dark matter transcripts".
内含子：An intron is any nucleotide sequence within a gene that is removed by RNA splicing during maturation of the final RNA product. The term intron refers to both the DNA sequence within a gene and the corresponding sequence in RNA transcripts.
区别：Intergenic regions are different from intragenic regions (or introns), which are short, non-coding regions that are found within genes, especially within the genes of eukaryotic organisms.
以上内容摘自维基百科。
简单来说，就是如下图所示：
