陪同 is used when you simply say you are companied by someone(physically). such as :when you are talking about a rule. e.g. 3歲以下的小朋友，需要有大人的陪同。 陪伴 is used when you wanna say someone is there(Physically+mentally) for you when something happened. e.g. 我因為有家人的陪伴，才走過這段不開心的經歷。 like Lucia said,an element of sentiment is involved.

To my opinion, 陪伴usually focuses on the more sentimental side, like 家人的陪伴，朋友的陪伴 the accompany of family/friends, While 陪同 is often used in a more formal way, for instance in newspaper"the president was accompanied by...."总统在....的陪同下....， or in a regulation “the child must be accompanied by his or her parents”孩子必须有家长陪同. Hope I can be of help. ^_^

No, technically 陪伴 is the same as 陪同 but it depends on the context whether to use one or the other. :) have a good day and hope this helps.

陪伴一般是一个较长的时间使用，陪伴不一定是人，有可能是某物或动物、植物等等。eg：这副眼镜陪伴我度过了初中时代。陪同一般指具体的某件事，或某类事。eg：特朗普陪同习近平参观访问了海湖庄园。