Hello, both have the same specs, with the exception of the SA255C1 is carbon fiber and the tm2515t1 is aluminum.
Those difference are, aluminum is a little heavier than carbon fiber, and carbon fiber offers a little less vibration, and allows for a little more of a stable video without the slight in and out blurs that can take place with nearby footsteps, or slight bumping.
Hope this helps, and it is of my own findings that are not documented, just observed with the difference in carbon fiber and aluminum.