Most people in the market, even some retailers and dealers, cannot tell aramid fiber and carbon fiber apart since they look very similar.  However, aramid fiber is totally different from carbon fiber.  The most important aspect to realize is that you should NEVER USE a carbon fiber case on your phone because it will BLOCK the signal significantly!  You can learn more about this from this blog:
https://www.ipitaka.com/blogs/news/carbon-fiber-phone-cases-just-say-no

Generally, aramid differentiates itself with carbon as follows:

Stiffness & Elasticity
Carbon fiber is extremely strong in tension and compression.  However, it is brittle, so the fibers aren't as tough as Aramid fibers.  Thus, a carbon phone case will also be brittle, whereas an aramid phone case will be tougher and more flexible.

Electrical Conductivity
Carbon fiber is very definitely conductive, whereas Aramid fiber does not conduct electricity at all.  In other words, a carbon phone case interrupts any signals being send to or received by your phone.  While the Aramid phone case has no affected on your phones signal strength at all.

Color
Aramid in its natural state is a light golden color.  It can be colored and many wonderful hues are now available. Carbon fiber is always black, and by itself, it cannot be colored. Remember, Carbon phone cases are always black.  However, Aramid phone cases can have several different colors.

For more information, you can learn from this page:
https://www.ipitaka.com/pages/material