Junior and Small fry

Junior noun - One who is of lower rank and typically under the authority of another.

Small fry and junior are semantically related In some cases you can use "Small fry" instead the word "Junior" as a noun or an adjective.

Small fry noun - A young person of either sex.

Junior and small fry are semantically related in young man topic. Sometimes you can use "Junior" instead the phrase "Small fry" as an adjective or a noun, if it concerns topics such as insignificant, minor, child.