Um, the first MLs could use Digital Light cases ("File Server" style) but from about LW 18+, the MLs and ELs both look like microwave ovens.

Programming is extremely similar from LW 15/16 (which could be in a hybrid digital/analog that looks like a small refrigerator).

The main difference between an ML and an EL is that the ML will usually support no more than 2 cases (i.e. ~128 ports not counting T-1s). EL will support as many as 7 cases. After LW 19 Rel. 3, I think it is, the ML was discontinued, and only ELs made from then on.

Pay close attention to the maximum number of ports permitted in Form 4 (also shown on the MOSS sheet). Also pay attention to the max number of BNIC and BONS cards, as this can lead to confusion in configuration.

Hope that helps.