What is the difference between a genotype and a phenotype? Is it possible to determine the genotype of an individual

What is the difference between a genotype and a phenotype? Is it possible to determine the genotype of an individual only on the basis of visual observations?

The phenotype is the internal and external parameters of the organism that appeared in it as a result of ontogenesis, that is, during its individual development. The phenotype is based on the genotype – a set of genes, possible mutations and environmental factors. For example – temperature, level, radiation, salt concentration in water. In organisms with a diploid or double set of chromosomes, only dominant genes appear in the phenotype. Recessive alleles most often do not appear in the phenotype, but they remain in the genotype and can be inherited by the body.
The genotype of an individual cannot be determined only on the basis of visual observations, because only some signs can be seen.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.