the estimate and uncertainty for experiment 1 is .15+-.01 and the .12+-.01 for experiment 2. Is the discrepancy between these two data sets significant? Why?

I would say yes, the discrepancy is probably significant, because the measurements should agree to within less than three standard deviations if they were measuring the same thing. These measurements differ by three standard deviations.

can you explain what you mean by three standard deviations? thanks

.15 - .01 = .14 the least result you should expect from experiment 1

.12 + .01 = .13 the most result you would expect from experiment 2

Well, this is significant. Your experimental results differ by more than the error bounds.