[talalyn]

Differences:
Marathon's lower anchor system slides on a bar when you change from rear to forward facing, Decathalon must be re-routed.
Marathon crotch strap is stationary, Decathalon can move.
Marathon's harness system loosens very similar to Graco where Decathalon has a button release that is hard for some people but most find no big difference.
Marathon has more available covers, Decathalon is very limited.
The only other big difference is that the Decathalon comes with padding for an infant so if you are using this from birth the Decathalon might be a better choice.
Size-wise and weight-wise they are the same.

	Forward Facing Car Seats A forward-facing car seat is one in which the child sits facing the front of the car. The seat should be installed in the back seat of your vehicle. Most forward-facing only seats are for children above 20 pounds.

	Britax Marathon - Click for more info Increasing the time a child can safely stay in their convertible car seat is a big issue and Britax engineers have come through in a big way with the introduction of the Britax Marathon with LATCH. A LATCH Compatible Convertible Child Seat, the Britax Marathon can be used rear facing 5 to 33 pounds and forward facing from 20 to 65 pounds. Compare the numbers and you will see it is hard to find a seat with these weight limits that is safe and functional.

	Graco - Click for more info Graco is one of the world's best known and most trusted juvenile products companies. They started the entire juvenile products industry with an invention called the Graco Swyngomatic. Since then they have invented products that have changed the way that parents travel with their children such as the travel system, which has made it so parents can lock an infant car seat into a stroller easily, without waking their sleeping baby. Their Graco SnugRide Infant Car Seat is pretty much synonymous with the term “infant car seat” because of its safety and design features coupled with its affordability. Today Graco continues designing and developing top-quality products that inspire parents and keeps children safe. Check out the new Infant Safe Seat Step 1 and Toddler Safe Seat Step 2 for proof of Graco’s continued commitment to child safety.