Herbal Medicines involves the use of plant parts-such as the leaf, root, bark, seed or flowers- or sometimes the whole plant. Generally the medicines are gentle in action and side-effects are rare, but that does not mean they are safe in all circumstance. Cautions are often stated on labels and there are documented reports of inter-reactions between prescribed and herbal medicines.
Homeopathic remedies are taken from the natural world and would be prescribed on the principle that you can treat it like with like.
An example of this would be giving a patient suffering from insomnia minute doses of caffeine which would help the patient to sleep naturally. Homeopathy however is patient-centred and would be recommended by a homeopath based on the individual symptoms.