Two layers of you
Genetics keeps two layers carefully apart. Your genotype is the set of genetic instructions you carry — the actual versions of genes written in your DNA. Your phenotype is what those instructions, together with your environment and life history, actually produce: your observable features, from eye colour to height to blood type. Genotype is the recipe; phenotype is the meal that lands on the plate.
Why insist on the distinction? Because the same genotype can give different phenotypes, and the same phenotype can come from different genotypes. A plant with the genes for tallness stays short in poor soil; two people can both have brown eyes while carrying different hidden versions of the gene. Keeping the layers separate lets us reason clearly about both.
Alleles: different versions of a gene
Here is the missing piece. A gene is not a single fixed thing across everyone — it comes in alternative versions. An allele is one particular version of a gene. There might be an allele of a flower-colour gene that tends to make purple flowers and another that tends to make white ones. Your genotype, in detail, is which alleles you carry; your phenotype is the feature those alleles help build.
In everyday genetics writing, “genotype” is often used for just the alleles at one gene of interest — for example, the two flower-colour alleles a pea plant carries — rather than the whole genome. Context tells you whether someone means the whole genetic make-up or one gene's worth. Either way, the genotype/phenotype split holds.
Gene of interest: FLOWER COLOUR
Alleles present: P (purple version)
p (white version)
Genotype → Phenotype (what we see)
-------------------------------------
P P → purple flower
P p → purple flower (P version masks p here)
p p → white flower
Same phenotype (purple), two different genotypes: PP and Pp.
The instructions (genotype) and the look (phenotype) are
related, but they are NOT the same layer.