Amazingly different in size

Juz now Z. 小姐 insisted that the two batteries (newly bought batt - blue enclosed, old batt - purple enclosed) are slightly different in sizes, so much so that she couldn't get the laser_pt.er to work using the new batt. I took a look at both batt briefly and told her both are AAA batt, they are of the same type and size, and should fit the laser_pt.er just the same. She don't believe. If theoretical can't work... use the practical approach. So I took it over and fixed the batts in and showed her. There's very slight connection problem but should not be an issue to get it working. Hmm...