I was told there was a difference between Rurouni Kenshin & Samurai X but I've only seen Rurouni Kenshin. Are they really different and if so can you explain how?
No, there isn't. It called a localisation editing.
Localisation is an essential process in releasing anime outside of Japan. It can cover a range of different processes depending on the individual title and the desired result. At its most basic level, the localisation process is responsible for deciding on romanised character and term names, as well as episode titles
No, there's no difference.
In 1999 Sony tried and failed to market the series in the United States as Samurai X via an existing company. The TV series was later licensed in North America by Media Blasters, who split it up into "seasons", and released on DVD.
The Wikipedia article links an Anime News Network article from the same time period, which says:
Similarly, EX Online is reporting that Sony's plans to market Ruroni Kenshin in the US as "Samurai X" by means of an existing company have fallen through. However, since Sony's raid on fansubbers carrying the series, no new plans or partnerships have been announced by anyone. ANN will be asking around about this and come to a conclusion about this one at Project A-kon this year (by process of elimination, we hope), but meanwhile, or contact at Sony has stopped returning our e-mails.
So Samurai X was just the name Sony came up with when it was trying to do a US release of Rurouni Kenshin in 1999. Media Blasters called the series Rurouni Kenshin for its US release, but ADV later reused the Samurai X name when it released the Rurouni Kenshin OVAS and movies:
The English-language versions of the OVAs, as well as the film, were originally released as Samurai X in North America, although the original name was included on the later DVD and Blu-ray Disc releases.
ADV Films released the series on two VHS or DVD sets in 2000 under their Samurai X name in North America, and the film version in 2003.
Sony actually did produce a dub of the series under the name Samurai X:
Sony Pictures Television International created an English-language version of the series, titled Samurai X, that airs outside of the United States.
The Wikipedia article includes links to Animax Asia and Animax Latin America for Samurai X, though the links are down now.