There are quite a lot of similarities, due to them both being inspired by TA (Total Annihilation).

Here is a quick list of possibly the main differences in the comparison.

• BAR is much closer to TA‍
• BAR is able to handle more things with less or no lag (battle with up to 3K units will play lag-free and up to 60+ fps with modern (3-4yo) hardware.
  ‍Side note: We are also working relentlessly on upgrading the main engine to modern GL which improved the already good framerate/low lag to 3-10x more fps.
• ‍SupCom has larger maps » or at least it takes units longer to cross a map - BAR is more intimate and generally has a tad smaller maps
  However, this little decrease in size, as we see it, is the sweet-spot for an RTS where you want to both be in strategic-zoom and in (closer-up) tactical-zoom levels - so you can enjoy the real battles more from up-close, instead of (mainly) moving strategic icons around.
• BAR possibly has quite some more / useful / interesting commands / features / options that can make playing and controlling your units easier. We have had several players from SupCom FAF talking after playing with BAR controls, they now don't want to go back to SupCom FAF anymore.
• Supcom (FAF) has 4 factions each with around 101 units per faction » BAR has 2 factions with around 195 units per faction.
  ‍Side note #1: BAR has a 'Scavenger Faction' with all but slightly modified units from the 389 regular units from Armada/Cortex + 21 unique Scavenger units.
  Side note #2: BAR has 50 unique alien chicken/raptor monsters, including 6 queens, you can fight‍
• BAR has much higher quality maps in general. Finer details, higher resolution textures (up to 16K).
  ‍Side note: Though we know Jip is trying to tighten that gap with new techniques for FAF-mapping based on how we make them for BAR‍
• Supcoms T4 Experimentals are bigger. BAR T3 Experimentals are a little smaller, but since they also less costly, chances are quite better to actually see them in a game of BAR than Supcom
  Side note: BAR also has T4 Units for the Scavenger Faction that are really big and super deadly
• Supcoms Interface looks more polished and has some nice eco-info stats and intel » though the plan for BAR is to implement more/better UI windows/intel as soon as we get our infra up-and-running and probably also when we can fully switch to the new engine with modern GL.

By the way, if you are coming from Supcom/PA or other related game you will probably find this guide very useful.