Lung squamous cell carcinoma and lung adenocarcinoma are the main subtypes of NSCLC. These subtypes, which start from different types of lung cells, are grouped together as NSCLC. Though lung adenocarcinoma and lung squamous cell carcinoma have drastically different biological signatures, yet they are often treated similarly and classified together as non-small cell lung cancer.
Increasing evidence suggests that lung adenocarcinoma and lung squamous cell carcinoma should be classified and treated as different cancers. Please refer to the paper I have attached below for your reference.