I prefer the phrase "large scale outcome" or "Large scale implementation" to the more generic "large scale change". Why? When the words outcome and implementation are included it feels more active, more directive, more specific.
For example, it is possible to have a large scale change that is not resulting in the outcomes you set out to achieve. A huge amount of change can happen and yet only a small scale impact is achieved.
Equally it is possible to have a large scale impact from a a small change that might affect only a small scale (numbers and geography). Using Pareto analysis can provide organisations with hints on where to leverage the smaller changes for the bigger impacts.
By focusing on impacts, by elevating the results we want, we can design organisation and system interventions to deliver targeted outcomes. In my experience, many groups who talk of large scale change are ending up creating busy-work that is not specifically directed at delivering a large scale outcome. For me change does not equal outcome or impact.
I'm reminded of a quote from Thoreau which runs along the lines of "It is not enough to be industrious; what are you industrious about?"