Both eMatrix and Fraxel Resurfacing systems do create some permanent changes in skin tissue. How much is noticed by you (or others) depends on your initial "problem" and the energy levels applied.
Fraxel is a laser and eMatrix is not a laser as the energy type used is not the same.
Fraxel (Restore, not the Repair*) uses focused laser energy to superheat the skin in linear columns to create a thermal response. When you heat skin tissue, the desired reaction is new collagen formation. The single drawback to Fraxel or other true laser as opposed to nonlaser energy such as Radio Frequency (as in eMatrix) is the higher degree of risk for post treatment hyperpigmentation with skins that have more pigment producing cells. (*The Fraxel Repair is a CO2 laser which actually vaporizes columns of tissue - for comparatives this response refers to the Restore which is erbium laser)
Fractional vs Full surface technology: Because fractional laser does not treat the entire skin surface, you have far less downtime and risks as with full surface laser and accordingly, you have a lesser response to the treatment. This is why most patients will require more than one session to get appreciable results for anything more than mild sun damage or textural irregularities.
eMatrix also uses focused fractional energy but it is Radio Frequency energy, not laser. The thermal response is not confined to a column as laser is - it tends to spread out more broadly beneath the top layer of the skin, so you get the collagen response without a direct corresponding level of external damage to the skin.
The company has termed the effect as "sublative" in that much more is going on than you actually see....somewhat like a pyramid shape as the heat energy fans out after it penetrates the skin. For the most part, RF energy doesn't stir up melanin production so it's seen as a more desirable treatment for some skin types.
Collagen response continues after the superheating from either system for about 6 months at which time what you see is the final response.
As far as stopping the signs of aging, we continue to age no matter what process we apply to our skin, and collagen breakdown will continue as before - With Fraxel or eMatrix you just got a push back in time with the new elastin and collagen fibers your body created as a result of the heat energy.