Thanks!

Anyone mind giving an example for a glass ball?

I second the Niko Rittenau recommendation.

I fail to see any lack of distinguishing as I do not see any claim on suffering or capacity to suffer in insects, only on insects' abilities to feel pain.

How physical pain relates to subjectively perceived suffering is a whole other topic, and as far as I can tell no subject to this review. (Though I've only read this post, not the review itself.)

I do see that pain-feeling is usually perceived as something innately suffering-inducing, and I see why that's the case. If pain is not somewhat negative for the organism experiencing it, why would that mechanism establish itself across whole species in the first place? Could be that pain in insects acts merely as a reflex trigger and no experience/suffering in the moral sense is involved at all, but I really argue that this is a whole other claim and topic.

The Open Phil report you linked shows quite well how little we know and how complex this issue is, and that jugdements rely heavily on claims and intuitions due to lack of understanding. 

So as we do not really know how the ganglions of insects (let alone our brains) work and what consciousness or conscious experience really  is about, I' be very careful with making definite claims about the suffering capacities of other species. 
As far as I can tell, the authors of this review made a good job of evaluating the physical ability of insects to feel pain. This is but the first step to assign moral patienthood to insects; it's a necessary, but not sufficient criteria. 

The likelihood of an organism to be able to suffer is significantly higher if that organism is known to feel pain. I personally tend to err on the worse case and assume  pain-feeling organisms are suffering, rather than risk neglecting substantial suffering as the odds seem high enough. (But that's just my personal take.)

I see how the concepts get mingled up inappropriately, but I would not go as far as to demand a clarification on that from any scientific publication dealing with pain (in organisms other than human), especially since there is no sufficiently backed-up concept of consciousness or moral patienthood. In my opinion arguing about wether pain-feeling and suffering can be used anagolous should happen, but it's probably not the responsibility of the authors here.