The A5 is a multi-effects unit providing five digital effects organised in a single effect chain - the Multi-FX version is so called because it's intended to be used as a multi-purpose effects unit, whereas the Guitar version has been optimised for a specific instrument. Well, that's the intention, but if technology was only ever used in the way the manufacturers intended it to be used, we'd all be poorer for it (and that includes the manufacturers, too - sampler manufacturers, for instance, have benefited greatly in sales terms from their instruments being used to lift breaks off records, surely an application which they never envisaged). And so it is that the A5 Guitar unit's inclusion of distortion and overdrive effects needn't preclude it from being used with synths, samplers and drum machines.
In fact, the only differences between the two versions, aside from the cosmetic one of colour-coding to enable ready identification (red stripe for Guitar, blue for Multi-FX), are that the Multi-FX version has an exciter effect while the Guitar version has distortion and overdrive and the two versions have different sets of ROM preset effects patches reflecting their different applications.
