I was curious to figure out if our backyard bush was indeed a blackberry or perhaps instead, a black raspberry bush.
After some research online (isn’t google grand?), I am now fairly confident that we have a BLACKBERRY bush, not raspberry.
The big difference is the way the stem affects the berry. A raspberry has a hollow opening when picked, the blackberry does not.
Here is a close up of some organic raspberries I bought a few weeks ago:
And here is a photo of a few of the blackberries picked a few days ago from the backyard bush. The blackberry has a white core from the stem.
I found this web page on wikihow that explains it very well, with photos too.