Balance means both parts are working equally well. If they are not, then imbalance occurs. This shows up as dizziness or vertigo. Sometimes both are impaired, but often it is just one. In some people both ears are involved, but for most, it remains with one ear.
Conductive impairment is about the mechanics of the transmission of the sound waves.
This can happen when the ossicles can't conduct sound to the inner ear. This is often reparable once the underlying cause is dealt with. These are usually not reparable. Here are several excellent articles on this subject. Causes Hearing loss has many causes, but for our purposes as a Meniere's site, tinnitus, is probably one of the major symptoms.