indistinguishable

exactly alike; incapable of being perceived as different

• “rows of identical houses”
• “cars identical except for their license plates”
• “they wore indistinguishable hats”

not capable of being distinguished or differentiated

• “the two specimens are actually different from each other but the differences are almost indistinguishable”
• “the twins were indistinguishable”
• “a colorless person quite indistinguishable from the colorless mass of humanity”