As an optometrist I can say SantiagoDR is essentially right, but also completely wrong. Yes the BC and DIA are essential, and of course the D(iopters) are vital.
70% of the contact lens wearers will be fine using these 3 parameters.
Unfortunately all major manufacturers use different production techniques, and materials. Some use a spin-cast production, either on the front or backside of the lens. Others use a combined technique of spin-casting and carving, etc...
The 3 major manufacturers also use different materials. I would hesitate to say if one is better than the other, but I can say that people react differently to those materials.
So, if at all possible, stick to the brand and the exact model you are wearing now. If you are a sensible contactlens wearer you should have glasses as well. If you do not find the exact same lenses here, I would propose to wear your glasses, and order your lenses online. They should be here within a week.
You only have one set of eyes, and if you get a serious infection once with lenses, chances are big you will never wear lenses again.