Alleles vs. Genes:

Alleles:
- Alleles are different forms of a gene that can occupy the same position on homologous chromosomes.
- They are responsible for the variation in traits among individuals.
- Alleles can be dominant or recessive, where the dominant allele masks the expression of the recessive allele.
- Alleles are located on specific loci on chromosomes.
- They can be homozygous (two identical alleles) or heterozygous (two different alleles) for a particular gene.

Genes:
- Genes are units of heredity that are passed from parents to offspring.
- They are segments of DNA that code for specific proteins, which in turn determine traits.
- Genes can consist of multiple alleles that determine variations in traits.
- They are located on chromosomes within the cell nucleus.
- Genes can interact with each other and the environment to produce a wide range of phenotypes.

Major Difference:
- The major difference between alleles and genes is that genes are the units of heredity that determine traits, while alleles are different forms of a gene that can produce variations in those traits.
- Genes are the overall instructions for a particular trait, while alleles are specific variations of those instructions that can result in different phenotypes.
- Genes are inherited from parents and passed down through generations, while alleles are the specific versions of those genes that can be inherited in different combinations.
In conclusion, genes provide the overall blueprint for traits, while alleles are the specific variations of those genes that contribute to the diversity seen within a population.