A pugh clause says that if they do not include all of your acerage in a unit, they will release the other acres and allow you to lease those acres with another driller. But what are the chances of another driller wanting to lease and develop your remailing acreage? Depends on how many acres you have. A general rule of thumb is large amount of acres, go for a pugh clause, or a set amount of the acreage leased that must be included be included in any unit. Some will say if it is a couple of hundred acres or more you want a pugh clause.
An all pool clause says they have to include all your acerage in the unit, This is what you want if you have a smaller amount of acres.