Every standard feature of pfSense is supported on both the standard and embedded platforms, but certain packages are not. The Squid web caching package, for example, required extensive writing to disk and should not be run on a compact flash drive.
There is a third type of image called Netgate ADI, which is designed and optimized for Netgate embedded appliances that run pfSense. If you are installing onto one of these appliances (for example, the SG-2440), you should use the Netgate ADI.
First, we should review the package we've chosen to install:
Based on this and the overall convenience of compact flash cards, we're going to install the embedded version of pfSense.
The standard image is meant to be installed on a hard drive. The embedded version is meant to be installed on a compact flash drive. Compact flash drives only have a limited number of writes during their lifespan, and the embedded version of pfSense is designed to limit writes to the disk for that very reason. That being said, each platform has advantages and disadvantages:
Entire drive must be overwritten
Fast access times
Cards can be easily swapped (backups, upgrades, and so on)
Requires little power
Designed to work optimally with Netgate pfSense appliances
Not designed to work with non-Netgate hardware
Refer to the pfSense online documentation: Versions of pfSense and FreeBSD: https://www.netgate.com/docs/pfsense/releases/versions-of-pfsense-and-freebsd.html