孝敬 (= 孝 + 敬 "respect") means "to take care and respect one's parents"; 孝順 (= 孝 + 順 "obey") means "to take care and obey one's parents" . Both terms share the core meaning of 孝 "filial piety" and are near-synonymous.
孝敬, if not referring to filial piety, means 敬獻, that is, "to show respect to someone by presenting gifts as a tribute". The word 孝 in this case is in its figurative sense, meaning "to respect someone as if he/she were the parent". Teachers are highly honored and respected in the Chinese society and so you may bring a gift to your teacher and say: "这是孝敬您的". But if you bring a gift to your boss and say "这是孝敬您的", it can be construed by some as "servile".