If there is no difference, why would one be better than the other?
When to use it?
Given the trade-offs above, the ideal case for render cells is when using large layers with lots of static objects. Remember unlike collision cells, this can include parallaxed layers. For example an ambitious game may involve thousands of scenery objects strewn across a huge layout. Providing few of those scenery objects ever change, then enabling render cells for the layer should save a lot of work checking whether or not thousands of far-away objects are in the viewport.
Remember render cells can be enabled or disabled for individual layers. So you can enable render layers for a "static" background layer with rarely-moving scenery objects, and leave them disabled for other layers where lots of action happens with moving objects.
When to avoid it?
Any layers with lots of changing objects - either creating, destroying, moving or changing Z order - will probably incur more extra work than is saved by the cheap viewport checks. Also single-screen games should definitely not use render cells, since there is never much off-screen that needs skipping! The game will only be burdened with pointless extra work. In these cases using render cells could actually reduce the framerate.
As ever, the key is to measure performance. If it's right for your game, you should be able to identify a measurable improvement to the framerate or CPU utilisation as measured by Construct 2. Don't turn it on assuming it will be faster - it could in fact be slower!