Each parcel you buy on the OUTERLAND Estate (or anywhere else in Second Life) has two important technical characteristics: area (measured in sqm) and prim capacity. Area is easy to understand, of course. Prims are a bit more of a technical issue: everything you see in Second Life (aside from land and avatars) is build from prims (promitive objects). This includes houses, trees, flowers, other plants, furniture and even waves.
As a rule of thumb, you need more prims if you want to place ("rez") more, bigger and more complicated things on your land, as if you only need a few relatively simple objects.
Projects
> High Area/low prim land
> Anwin Boardwalk
Both characteristics, area and prim capacity, of a parcel depend on each other: if you need more prims, you have to buy a parcel with a larger area. If a parcel is bigger than another one, it usually can carry more prims, too (more complex buildings).
The relationship is not always the same, though. We sell two types of land on the Otherland Estate currently:
A full region (or "sim") of full prim land can carry 15,000 prims. This means that a typical parcel with a size of 4096 sqm (1/16th of a full region) has a prim capacity of some 937, a parcel of 8192 sqm one of 1875 and so on.
This classic type of land is standard on the so called "mainland", which is controlled by Linden Lab and you can find it on the OUTERLAND ESTATE, too.
A lot of the land on THE OUTERLAND ESTATE is Large Area/low prim land (what Linden Lab calls "Homesteads" these days), though. You get four times the area of land here at a slightly higher price - but have to accept a reduced prim count.
For example: a parcel of 16,378 sqm (= 1/4 of a full region) has a prim capacity of 937. Thats is the same capacity as a parcel on 4096 sqm on full prim land. But you only have to pay a little more for the Large Area parcel than you would have to pay for the full prim land with the same prim capacity ... but you get four times the area!
Large-Area regions are for those who want to have a little more elbow room and live a little more secluded.

Most of this land is designed as islands in the sea. But we have some non waterfront land in the Large Area/low prim type, too.

Land on High Area Sims comes in two different parcels sizes typically: 16,384sqm or 32,768 sqm.
You can buy a whole sim with a full 65,536 sqm, too, of course and get a prim allowance of 3750. Send an IM inworld to Julienne Caudron or an email to land@otherland-group.com, if you are interested in owning a full sim of 65,536 sqm or more.
WARNING: If you want to very large and complex buildings, or want to use a lot of scripted objects on your land, Large Area/low prim land might not be the right choice for you! Linden Lab has only certified this type of sim for non demanding use. Some scripts run slower on low prim land, for example. You will rarely notice that, though. There are many other factors determining performance (or "lag") in Second Life. Most of them are much more important that the type of land you are on.
In addition, Large Area/low prim land has a limit of 20 avatars per region/sim. Please take this into consideration if you plan on doing events to which you would like to invite more than a small group of friends.