Explain how two organisms can have the same phenotypes but different genotype s?

Genotypes are the different allele combinations that an organism has, while phenotypes are the traits that show up physically.

So, two organisms can have the same phenotypes by looking alike, but their genotypes may be, in fact, very different.  Homozygotes for the dominant allele and heterozygotes will both have the same phenotype. Organisms have the same phenotype, or physical characteristics. They do not however, have the same genotype, or genetic makeup. If T represent tall, and t represnts short then the organism will have the genotypes TT and Tt. If you make a  Punnett square you will have the same phenotype but different genotypes.  

That is true! many fish species traveled to the u.s. because of it.