Corporate identity is a carefully thought out system of visual identifiers which, in addition to the basic components (logo, font, colour), can include a huge variety of recognisable elements (video clips, rules for combination decorative elements, fonts, objects, decoration and more).
So сorporate identity is broader concept than сorporate style. Its aim is to help a company to reflect its purpose, character and mission. And of course to add personality at the same time.
How to distinguish good style from the bad?
The first is that you won’t want to remake it in half a year.
The second is that it is convenient and practical. And this is easily determined, because a good corporate style you have no problem using both on a pen in a couple square centimetres in size and on a huge banner.
The third is that your clients like the style.