A full container load is a standard 20 or 40 foot container that is filled to maximum capacity by one buyer (either an individual or a company). Full container load shipments are often cheaper than an equivalent weight of cargo in bulk.
When you occupy a partial container load, you pay a higher price per foot. Think of it like buying wholesale items: The more you purchase, the greater the discount.
When shipping items in large bulk, it's best to hire a customs broker to evaluate your items and make sure it complies with all the necessary regulations. You can checkout the guide here on what to look for in a customs broker.