A ronin is a samurai.
Samurai was a status in Japan. A ronin was simply someone of samurai status that had no clan affiliation.
A samurai without a lord was called a Ronin
Ronin are samurai without a master
When a Samurai has no master, they are referred to as Ronin I believe.
The difference between a shogun and a samurai is like the difference between a king and a knight.
Ronin who were master-less Samurai .
they are the positions in which a samurai serves his daimyo
The samurai were responsible only to their master who in turn were part of a chain of alliances ranging up to the emperor. Samurai had no lateral responsibility and if told to attacker kill an equal would do so without hesitation. Ronin (masterless samurai) were pretty much on their own. Challenges were e met, failure to accept challenges was not an option for samurai or ronin.
You may may be thinking of 'Ronin', who were Samurai without a master to serve.
A masterless Samurai is called a 'Ronin' (literally: drifting person).
Rurouni Kenshin or Samurai Champloo
Emperor, Shogun, Daimyo, Samurai*, Peasants, Artisan, and Merchants. *There are also Ronin, which are Samurai without a Daimyo (because he/she was killed, committed seppuku, etc.).
In the mid-evil time like the Saxons and Germanic tribes, the Japanese developed an advanced feudal system. On the Bushi fighting scale the Samurai was the warrior before you became a Samurai your title would be Ninja the lowest rank on the Bushi fighting scale. Samurai usually always served under a shogon who was their master, and would send Samurai off to fight other tribes and factions in mid-evil Japan. there were also Daimyos who would hire Samurai for protection of their estates and families. then there were also Ronin who were "Masterless Samurai" Ronin were first Samurai but if a Samurai's Shogon or Daimyo dies they are no longer their vassels and are free to raom sworn to no-one. Ronin were usually Mercs. The Samurai were used as the perfect fighting machine and were basically in a sense Japanese Knights or vassels.