According to this knowledge base article from Dell:
Newer Notebook systems are utilizing Intel 4th Generation processors that require a new type of memory SoDIMM known as DDR3-Low Voltage or "DDR3L".
[...]
DDR3L is pin-compatible with DDR3.
DDR3L is a dual voltage capable memory SoDIMM, which supports operation at both 1.5V and 1.35V.
[...]
DDR3 is a single voltage capable memory SoDIMM, which supports 1.5V operation only.
It is NOT compatible with systems using 4th gen Intel processors, which exclusively support 1.35V operation for memory.
Since you're running on 1.35V and on a 5th Gen mobile processor I'd suggest buying a DDR3L model. Since this is an Dell articile I'm not sure if this limitation (4th Gen) is only applicable for Dell notebooks or universal, but since DDR3L is compatible with both specifications it's a safe bet.
DDR3 sticks might not work in this environment if your laptop does not support 1.5V operation (which i'd suspect) and even if it does would not be as power efficient.
I don't think CPUZ is wrong with reading out DDR3 since DDR3L seems to be a sub-specification of DDR3 and is meant to just read out the generation (DDR1, DDR2, DDR3 or DDR4).