Here are the specification differences between Britax Marathon ClickTight and Chicco Nextfit Zip, so take a look at it to choose the right item for you.
Britax Marathon ClickTight
Chicco Nextfit Zip
Spec Comparison of Britax Marathon ClickTight and Chicco Nextfit Zip
ClickTight Installation System is the safest and simplest technology on the market: Open the front of the car seat, buckle the seat belt across and click the seat shut: That’s all you need to do for rock-solid installation
SafeCell Impact Protection is a safety system including a steel frame, energy-absorbing base, V-shaped tether to minimize seat rotation and staged-release stitches that slow and reduce forward movement during a crash
Side impact protection, formed by a deep foam-lined shell, absorbs energy and shields your child from the most dangerous type of collision
Recline Sure 9-position leveling system provides the most recline options of any convertible seat for an accurate fit in a wider range of vehicles
Two Ride Right bubble levels indicate correct seat angle in both rear-facing and forward-facing modes
Exclusive Super Cinch LATCH Tightener uses force-multiplying technology to help achieve a tight and secure fit with a fraction of the effort!
Zip & Wash seat pad easily zips out from shell
Comfort Flex harness management with padded, flex-out design keeps both sides of harness waist belt up and out of the way for easy in/out!
Recline sure 9-position leveling system for an accurate fit in a wider range of vehicles