Given this has caused some confuion over differnt images, I figured it was about time to write up a summary of all the factions and their traits.
The Hiigarans have always placed survivability above all else. No matter which Hiigaran faction you play, you will have a balanced fleet at your disposal. The Hiigaran fleets operate best when expertly coordinated to fight as one unit, often using large numbers of frigates to defend the main attack fleet.
The Hiigaran Defense Fleet was designed to protect the Homeworld and it's outlying Colonies. This fleet focuses heavily on defensive operations supported by selected offensive units. When playing this fleet, expect to fight very slow battles, focused on you outlasting your opponents while using steady firepower to depleet their resources.
Subfactions: Response Fleet, Strategic Fleet
The Hiigaran Expeditionary Fleet is the mobile arm of the Hiigaran Navy. They often operate outside of hiigaran space and are adept at dealing with unusual circumstances. The Expeditionary Fleet generally forgoes armor in favor of speed and mobility and is crewed mostly by veterans.
Subfactions: Exploratory Fleet, Deep Space Fleet
The Vaygr factions are generally offensive warriors. They prefer to assault and destroy rather than outlast their opponets, often using numbers, strike craft or cheap tactics to gain the upper hand. The Vaygr factions are also highly independant. Their fleets are not required to stick together to maintain combat efficiency, meaning they can more easily execute flanking or ambush maneuvers from multiple directions at once.
Task Force Venom
Task Force Venom is the raiding faction of the Vaygr fleets. It's combat doctrines are highly split, capable of adapting a pirate combat style which focuses on disabling and capturing enemy ships or a raiding combat style which focuses on obliterating the enemy while offering no chance of surrender. Task Force Venom posesses many EMP or disabling technologies but forgoes larger ships in favor of smaller combat groups capable of operating autonomously.
Subfactions: Raider Doctrine, Pirate Doctrine
Task Force Overlord
Task Force Overlord is the main offensive arm of the Vaygr fleets. It uses numbers and overwhelming firepower to crush its enemies or take their Territory for the Vaygr's Great Crusade. Unlike Venom, Overlord has little interest in disabling their opponents, preferring higher damage output to controlling the combat flow. Task Force Overlord brings the greatest ammount of firepower of any faction to bear but suffers from having to cut corners in production in order to maintain their large fleets.
Subfactions: Invasion Doctrine, Warlord Doctrine
The Keepers are generally hard to classifly. They can adapt many combat styles which all tend to focus on the use of capital ships supported by Drones and Autonoms. Their ships, despite their age, are incredibly sophisticated and small numbers of them can bring astounding firepower to bear. When engaging the Keepers, you are well-advised to stock up on anti-capital ship weapons.
Keepers of Sabtah
The Keepers of Sabtah are one of the newer Keeper fleets. Despite this, they have guarded their masters relics for thousands of years prior to becoming active when the Eye of Aaran was activated by Sajuuk. The Keepers of Amun use Phase Shields and advanced capital ship weaponry or armor to gain the upper hand in combat. Engaging this Keeper fleet head-on may not be the best tactic as they will most likely deal more damage and survive longer than you will.
Subfactions: Extermination Runtimes, Pacifier Runtimes
Keepers of Amun
The Keepers of Amun are an ancient Keeper fleet which has bided its time for several millenia, waiting as their ships slowly decay with time. However the core technology their fleet was built on is as efficient today as it was when the Amun fleet was created. Unlike other Keeper fleets, the Keepers of Amun have fought millions of battles against many foes, always adapting their combat style for the best results. They are masters of hit and run tactics as well as crippling enemy fleets.
While having access to many ancient Progenitor technologies no other race has heard of, the Keepers of Amun lack more 'modern' Progenitor technology developed after their fleet was created.
Subfactions: Pharaoh Protocols, Reverant Protocols
I hope this summary was able to give an overview of all the different factions, their strengths and their weaknesses.