Is this calleyeranna or betufolia?

[Yarg]

This is a invasive thicket on a dead-end road... and I've seen calleyerana thickets but without thorns.. what do you about think?

 

[Lucky_P]

Have seen claims that betulifolia is out there crossing with callery, and that some of the bazillion invasive 'volunteer' pear seedlings popping up all over the country have some betulifolia in their genetic makeup. Certainly the vast majority of 'callery' seedlings around here are thorny as all get-out.
I'm not enough of a botanist to differentiate callery from betulifolia.

 

[Telemark]

Callery.