Arial vs Helvetica
Arial:
Designed in 1982 by Robin Nicholas and Patricia Saunders for Monotype (not Microsoft), it’s classified as Neo Grotesque, was originally called Sonoran San Serif, and was designed for IBM’s bitmap font laser printers. It was first supplied with Windows 3.1 (1992) and was one of the core fonts in all subsequent versions of Windows until Vista, when to all intents and purposes, it was replaced with Calibri.
Helvetica:
Designed in 1957 by Max Miedinger, Helvetica’s design is based on that of Akzidenz Grotesk (1896), and classified as a Grotesque or Transitional san serif face. Originally it was called Neue Haas Grotesque; in 1960 it was revised and renamed Helvetica (derived from Confoederatio Helvetica, the Latin name for Switzerland).
Most people hate arial because it seems to be an unadulterated rip off of Helvetica, by Microsoft (please see above for sitation), which contained limited aesthic changes to bypass copyright laws in order to be used as a Microsoft screen font. I personally find this to be a bit of a shame, and more to the point, untrue. It is true to say that Arial is significantly similar, and in my opinion, based on Max Miedinger's near perfect font, however, as I am constantly reminded ... "Imitation is the sincerest form of flattery", attributed to Charles Caleb Colton (1780-1832). i can think of nothing more flattering to his (and the foundrys) genius that someone would want to try and improve the work he had done in order to produce something that would hopefully improve upon, to be used in the next era of print and publishing.
What I have tried to illustrate above are the main differences when trying to idnetify the differences between the two, as it is sometimes very difficult indeed. For further reading and information, please refer to the links on the right hand side of the page.