Different purposes
Spam describes unwanted or unsolicited messages. Phishing describes a deceptive attempt to influence a sensitive action or obtain information. A message can be both, but an unwanted message is not automatically phishing.
Assess the requested action
Look at what the message wants you to do. A credential request, unusual payment instruction, or impersonated business task changes the security question. Professional formatting does not determine which category a message belongs to.
Use the appropriate reporting route
Your organization may have separate processes for unwanted marketing and suspicious communications. Follow the security-reporting process when the request raises a concern, even if you are unsure how to label it.