I'm going to assume you're referring to Holland America Line. I believe Holland and Barrett is an herbal foods supplier.
RCCL is a mainstream line that is known for great entertainment and plenty of activies aboard their ships. They are among the most family friendly of all cruiselines and have a good sampling of passengers in every age group. Their food and service in the dining room is probably better than average, although everyone has differnet tastes.
HAL is known as a little more of an upscale line. More formal than RCCL on formal and informal nights. The average age of passenger will be significantly higher than on RCCL or other mainstream choices. They are very well known for having among the best of food and service, again there are those who will disagree and don't like the food or choices on HAL. It's hard to speak in generalities about any line because there are exceptions to every rule of thumb on a given ship or sailing date. There will not be the variety of activities you'd found on RCCL. They do however provide comparable entertainment and shows to other lines like RCCL.
If you want to relax and be pampered with cabins that are a little larger HAL is a great choice. After hours there will be very little going on and few people out and about, again it's a much more senior crowd. If you're looking for a festive, nearly never ending source of entertainment and activities RCCL is your line. If you want linen, china and crystal with hardwood paneled cabin treatments and fine dining go with HAL. Also if you want to escape from families with kids, HAL is your cruiseline. There will be some but very few in comparison.