Is there such a thing as big and small labs?

Yes there is such a thing as big and small Labrador Retrievers. Want to know why? Because there are a lot of folks who do not know what a 'Breed Standard' is.

There are also folks who would breed their Labrador Retriever to another Labrador Retriever when they also do not know what a breed standard is, nor do they realize that they may be bringing into this world a smaller, skinner type of Lab or a larger, bigger type of Lab.