As you can see from the specs below, 1995 Neuron was mostly made from Columbus' new stronger UTS material (Nivacrom) which allowed the tubes to be drawn with thinner walls by 0.1-0.2mm compared to SLX, therefore lighter even with the new-fangled standard oversize tube arrangement of 28.6/28.6/31.8.
These larger diameter tubes produce a stiffer frame overall, despite the thinner walls. Since stiffness increases as a cube of diameter, but wall thickness increases just give a straight linear increase of stiffness, doubling the wall thickness = double the stiffness + double the weight; double the diameter = eight times the stiffness and double the weight. So designers then thin down the walls of the fat tubes to decrease weight, but too much risk buckling and denting. All tube specs are a compromise between these two factors)...anyway:
Butts are half the length of the SLX ones (60mm as opposed to 120mm).
Neuron also has the amazing elliptical butting, where the butts are thicker top and bottom or sides of the top, down, seat and steerer tubes.
The three main tubes also have SDS, a long internal strip reinforcement. This is designed to help resist denting the top tube from bars and reinforce the areas around bottle bosses braze-ons on the 0.5mm centre sections.
Conversely, SLX was designed over 10 years earlier as a heavy duty version of the venerable SL set, so was never a light tubeset, and ran the older 25.4/28.6/28.6 tube arrangement with thicker walls. The helical ribs on the main tubes (originally an option on SL steerer tubes back in 1980) were a fancy addition for the Columbus range at a time when Reynolds were forging ahead with the metallurgical wizardry of 753, but it added little other than 65g more metal to the set compared with SL.
Go for the Neuron frame. Still unmatched for utterly brilliant steel tube manipulation.
All the best,