an not easy to responsible question but i think i can help.
So intel smart cache is nothing "really new", so here you find a nice overwiew what it does: https://software.intel.com/en-us/articles/software-techniques-for-shared-cache-multi-core-systems/?w... Software Techniques for Shared-Cache Multi-Core Systems | Intel® Developer Zone
Summary: Its a enhanced caching-strategy
And the answer: Intel Ark are right with that
All Haswell based CPUs got the "old" Intel Smart Cache - so also the i5-4200U
With Broadwell Intel has to changed the Cache-Strategy in some ways because the integration of the new GEN8 Intel Graphics - so on the most Broadwells like the I7-550U the "old Smart Cache" are gone. But that dosen´t meens this cache is less smart ... its just the gap between marketing and real hardware