Question

What is the difference between an allele and a gene?

Answer 1

The following explanation may help.

Explanation:

The alternate forms of a gene pair are called alleles.

While

Genes are the characteristic units of hereditary which are transferred from the parents to the offsprings.

Alleles actually give the means of expression of a gene. For instance, we have a gene of height, then tallness and shortness are the two alternating phenotypes of this gene which are represented by the two alleles of this gene pair.
Moreover, Alleles are inherited in pairs but genes are generally not.

The following video may help. A quick guide about the difference between gene and allele