Pictures of two S 3/6 loks, one manufactured by Märklin, called the King Ludwig lok, and the other by Roco. There are distinct differences between the two loks. The Roco has good sound and the Märklin lok does not.
The Roco lok has a dark blue livery and the Märklin has a brighter blue livery which seems artificial. The Roco lok seems to have finer details than the Märklin lok. The Roco lok runs very quietly without the sound on. The Märklin lok is a little bit noisier. The Märklin lok seemed more responsive to IB commands at lower settings than the Roco lok. Both are digital.
The lamps on the Märklin lok are slightly brighter than the Roco lok, especially in the back of the tender. These are great looking engines on any layout and their pulling power seemed about the same with the edge given to the Märklin lok. My vote is for the Roco S 3/6, it has more detail, has sound, and runs well even on M track.
Pictures of two TEE VT 115 sets one made by Märklin and the other set by Roco. The first thing one notices is that the Märklin loks and coaches are metal, while the Roco set is entirely plastic.
In the Märklin set both the leading and the trailing loks have motors and they both have sound. The sounds in the Märklin loks come from both ends and are very realistic. When the direction is changed the Marklin loks make a change-over sound. The Roco set has sound only from the lead lok. It does have one sound feature that the Märklin loks do not have and that is the random sound of air releasing. The F4 function key will make this sound with the Roco set.
In the Märklin set, the F2 function turns on lights in the two coaches with a nice table-lamp lights in the first car. There are only two coaches in the Märklin set with a promise of three to come. The Roco set also comes with two coaches and already has an add-on set of three more coaches. Connecting the Roco coaches and loks is easy with a plastic bar.
Surprisingly, the Märklin connectors are easy as well but are current conducting. They snapped together quite easily but there is a warning in the instruction booklet not separate them frequently. Both sets have protective coverings between the cars that are spring loaded for realism as they round curves but the Märklin coverings are really neat and work well with no space seen between car.
The Märklin set is more powerful by far with two loks. It runs smoothly and is better controlled at lower speed settings. It starts well with lower speed settings. Both sets run well on my M track with some C track layout.
Before the Märklin set the Roco TEE VT 115 was my favorite lok set. Now the Märklin TEE VT 115 occupies that place.
Pictures of two BLS Ae 8/8 one made by HAG and the other by Roco. There are also pictures of a HAG BLS Ae 4/4 and an Re 4/4. These engine are powerful and finely detailed. Note the differences in the Roco and HAG engines. Both the Roco and the HAG Ae 8/8 have two motors. These are great looking engines on any layout but the HAG loks are definitely the better made loks with great pulling power. The Roco loks have slightly more detail.