Euploidy is a chromosomal variation that involves the entire set of chromosomes in a cell or an organism, resulting in a multiple of the haploid or basic number of chromosomes. Euploidy can be either a chromosome loss or a gain in the chromosome sets, and there may be a single set (monoploidy), two sets (diploidy), or multiple sets (polyploidy, i.e. triploid, tetraploid, pentaploid, hexaploid, etc.) of chromosomes. Other types of euploidy are autopolyploidy and allopolyploidy. In autopolyploidy, there is an additional set of chromosomes, which may be from a parent or identical parental species, while in allopolyploidy, the additional set of chromosomes comes from another species.

Aneuploidy, on the other hand, is a condition in which an individual has one or more chromosomes added or deleted from the normal chromosome number. Aneuploidy can occur due to chromosomal non-disjunctions during division, and it creates abnormality in the present species. While euploidy helps in the formation of new species, aneuploidy leads to disorders like Down or Klinefelter syndrome.

In summary, the key differences between euploidy and aneuploidy are:

Euploidy:

• Refers to the variation in the normal complete set of chromosomes in a cell or an organism resulting in a multiple of the haploid or basic number of chromosomes.
• Can be either a chromosome loss or a gain in the chromosome sets.
• There may be a single set (monoploidy), two sets (diploidy), or multiple sets (polyploidy) of chromosomes.
• Helps in the formation of new species.

Aneuploidy:

• Refers to the condition in which one or a few chromosomes are added or deleted from a chromosome number.
• Occurs due to chromosomal non-disjunctions during division.
• Creates abnormality in the present species.
• Leads to disorders like Down or Klinefelter syndrome.