I would say the colour will appear more uniform due to a thicker layer in total - less likelihood of what is underneath showing through, however slightly. This usually leads to the colour appearing somewhat richer or "firmer" - not a shade difference but more depth perhaps. Also I would say this might be described as more opaque (not less) but most of the difference is difficult to describe or quantify and very much "in the eye of the beholder". One thing to remember is that if there is a substantial time difference between coats then there will likely be a shade difference due to ageing and (unless taken care of) possible batch differences in the paint (especially shop mixed - if you have more than one tin/bucket of this then mix all together before starting to use).