The Institute for Transportation and Development Policy (ITDP) has published an updated Bus Rapid Transit (BRT) Scorecard. Now I know this post is about Light Rail Transit (LRT), but the scorecard was rewritten in a way that makes it easier to evaluate rail systems as well as bus systems, and after all they are only one letter apart in their acronyms.
And for anyone who is reading the article for this line alone, the METRO Green Line scored a 72.5 out of 100 (Silver level), while the Blue Line scored a 69 out of 100 (Bronze level). And both met the standard for basic BRT. (For reference, the Red Line scored a 51 out of 100 and was determined to not be BRT.)
Back to the Basics

Do not drive on tracks! This exclusive right-of-way does wonders in assuring a designation of “BRT”.
The big reasons that the METRO Green and Blue lines outscored the METRO Red Line, is in the section BRT Basics: things like “Dedicated Right-of-Way”, “Alignment”, “Off-Board Fare Collection” and “Intersection Treatments.” On all of these sections, both LRT lines scored very well. The Blue Line lost a few points over alignment (the ITDP says central in the roadway is better), the Green Line lost points for not having enough signal priority, and both routes lost points for using proof-of-payment fare collection instead of turnstiles.
The fact that light rail outscores the Red Line should come as no surprise, as all the basics have to be in place for a train system. A train does not mix well with cars or other vehicles nearly as nicely as a bus does, and you cannot have a train conductor checking tickets. (They’re in that little room.)
These high scores also are what matter when the “BRT” designation is handed down from the ITDP. Everything else makes the service nicer, but to quickly move many people, the basics are needed. This is also why building a true BRT continues to be a struggle; it’s too easy to cut corners.
Pretty Little Extras
Station design is the main place where the Green and Blue Lines differ. The Blue Line was superior in having more central stations (makes transfers easier, as well as saving on cost and not having to cross both directions of track ever at once), and having stations setback from intersections.
Meanwhile, the Green Line proved superior with its frequency of stations being considered nearly ideal for a transitway. Nearly the entirety of the corridor is within walking distance to a station.

The Charles Avenue Bicycle Boulevard at Lexington Avenue.

Union Depot’s bike parking also allows you to rent space for your bicycle inside, in a locked secure room.
Bicycling also carried a big role in how the scores of the Green and Blue Lines differentiated themselves. The Blue Line has the Hiawatha Trail and other improvements for bicyclists along much of its route. While not an on street bicycle lane, this infrastructure allows more people to use the system by letting bicyclists get to Hiawatha Avenue however they are comfortable, and to be able to access a station faster.
The Green Line is a little different, but I still gave it half a point (as opposed to the Blue Line’s full point) due to the Charles Avenue Bicycle Boulevard being two blocks north, and running along the U of M Transitway and Washington Avenue, all of which are reserved bicycling space. However, the Green Line has NiceRide at more stations, and has fully secure bike parking at both ends of the line. Whereas the Blue Line has… the underside of a MOA parking ramp… Which is covered, but dingy and not really what I’d call a secured bike parking area.

This was the door to the secure bike parking room. Unsurprisingly, they do not let unauthorized, informal bloggers to break in unannounced and without telling anyone.
Deductions!
For this portion, both the Green and Blue Lines failed to meet the needed frequency to avoid being docked three points each. Increasing the frequency to 7.5 minutes instead of the current 10 minutes might prove to be a challenge, but if and when the Blue Line’s ridership warrants it, it can join the exclusive silver level “BRT” club. The Green Line would also get more points, but it would remain silver.
Maybe someday.