Just curious, are all N100 or N95 respirator masks the same? I noticed 3M's masks are more expensive than others manufacturers'. Am interested in planning an emergency kit for my urban office. Thanks!

No they are not. First of all N100's amd M95 are made to diffrent standard.

The N100 and N95 designation are only standards the mask must pass to carry that designation. Manufactures can make them any way they like, aslong the meet the standards.

Some are fold flat, some have a valve, some are more comfortable than others, some have beter adjustable straps, etc. Pick one that has the features you prefer.

As PC2K points out, the N95/100 designation only tells you about how well it filters, but not about how well it fits, how small you can fold it, how durable it is, etc. Depending on its intended use, I would think that for an escape-type situation out of an office, a correct fit to your particular face shape would be the most important factor, and the rest are secondary considerations. An ill-fitting N100 is not going to protect you like you expect. However, if you're talking about something like bird flu and having to wear one all day, then the priorities change again.