Answers: A buffer relates to a portion of the total limit of liability required. For example If I entail a $10,000,000. limit of auto liability the primary company might agree to $2,000,000. I might find another company to agree to supply a buffer branch of liability of $3,000,000. and then arrange to hold an umbrella liability policy carrier supply the remaining $5,000,000. The umbrella policy one and only covers if the total loss exceeds the primary limit and the buffer branch limit.
Excess of loss is roughly a reinsurance term. For example, an insurance company might agree to insure a building (or buildings) next to total policy limits up to $10 million. If the insurance company does not want to retain such a colossal liability at one location it buy per risk reinsurance of $5 million in excess of $5 million. In this armour of a $6 million loss the insurer would pay the full settlement to the policyholder but would get better $1,000,000. from the reinsurer.