Sorry I'm new wt is pheno? Lol
Within a genotype (the main classification - for example Super Lemon Haze) there will be varying expressions of the various sources of the strains genetic history - these different types within the same strain are called phenotypes.
For example, Super Lemon Haze is made up of - Super Silver Haze (Haze x Northern Lights 5 x Skunk 1) x Lemon Skunk (Skunk x Citral). So there are five strains that make up SLH, with strains like Skunk themselves being made up of 3 other strains (Columbia sativa, Mexican sativa, Afghan Indica). So there is a massive variety of characteristics that can be expressed in strain. In much the same way as different children from the same parents can vary in eye colour, hair colour, height, facial appearance; cannabis plants from seeds from the same parents can vary on smell, height/stretch, taste, strength etc etc. These are both examples of phenotypic diversity.
Other factors like stability of the strains, and which stage of the genetic engineering process the strain is at, effect how much or little phenotypic diversity occurs. Landrace strains which are back bread within the same strain for generations show very little if any phenotypic diversity and are said to be homogeneous. An F1 hybrid of two unstable strains - which imo the GHS SLH is (albeit quality genetics) - will likely lead to high phenotypic diversity and lots of different plants of varying qualities.
Here are two distinctly different flowers, both from my Sugar Punch plants, to illustrate what I mean. Same strain, grown with seeds from the same pack.