Guaifenesin is an expectorant. It's used to thin mucous secretions. Most people that take bronkaid need it for COPD, the guaifenesin helps thin out all the mucous in the chest and the epehedrine helps open up the airways (ephedrine is a non-selective beta agonist, which is why it stimulates the heart as well as the lungs).
Ephedra was taken off the market due to adverse cardiovascular events (heart attacks). I'll let other people give you advice about which to take since I take neither.