Tosh/Marybeth: married mum, loves husband although not always perfect. Bit less confident. Brunette (although not sure if that's relevant).
Ruth/Christine: definitely not married. Entertaining love life with quite understandable, if ill-advised taste in partners. Trying to shake off the legacy of a prominent father figure. Glamorous blonde (very similar haircut..?). Twinkle in eye.
Admittedly, I am a bit hazy on the finer details of Cagney and Lacey because I was a young teen. I was VERY clear that I wanted to be Cagney! Did anyone aspire to be Lacey..?