Space Frontier features a choice of three factions for players to pledge their allegiance to. Players may switch factions by rejoining the server, however an important factor to remember is that, unlike your player level, your faction level will not switch over. Each faction has its own level that must be levelled up individually.
Each of the three factions have different beliefs and therefore specialise in different things.
Members of the Illumi faction fight for freedom an independence. Signified by the colour green, their guns tend to have lower recoil compared to others, and specialise in speed and accuracy.
Members of the Derept faction fight for power and control. They are recognisable by their red symbol. Their guns feature an increase in accuracy and/or walkspeed and their primary focus is speed and power.
Members of the Guard faction fight to maintain law and order. With their colour being blue, Guard guns deal more critical damage and focus on accuracy and power.