Whatever it may be
Whatever it may be, everything is similar in one way or another. In this case, a lifeboat, an island and Earth. All three have limited supplies that run out. In one way or another, all of these will run out. The life raft supplies will run out quickly, the island can only produce so much, and Earth’s natural resources are running dry rapidly. All will run out eventually.
All of these elements are able to hold and carry, everything from supplies to actual humans. The life raft may only be able to hold a small amount but it still has the ability to carry. The Earth is able to hold on a wide scale.
The three mentioned can also all sustain life. The lifeboat can only sustain until supplies run out, but the world can provide until it is destroyed. The island can last much longer than a lifeboat but it won’t last as long as the entirety of the world.
The lifeboat, the island, and the Earth are all solid forms of matter. They are all a dense solid and have volumes. They’re all made of atoms and are solids.
Finally, they each have their own gravitational pulls. The Earth getting it from the entire solar system, the island getting it from the Earth, and the life raft getting it from the atmosphere and water. They each have their own center of gravity and gravitational pull.
Although they are similar, they are obviously all very different. Firstly, the Earth is an ecosystem, but the raft and island aren’t. The earth can produce food and shelter for the islanders and provide supplies for those in the life raft, but they can’t provide back. The earth also has its own food chain and the raft and island don’t, they’re part of the Earth’s chain.
The raft is man-made, the island and Earth aren’t. Rafts were made by man to travel from island to island, land to land, to get where you need to go on the large Earth. We didn’t create the Earth to travel, we didn’t create it at all.
One of the most obvious differences would be size. A raft compared to the size of an island is like comparing an ant to a lion. An island to the entire Earth is nothing but a grain of sand. A raft to the world is a single cell in a large Oak tree.
Another notable difference would be the raft being a sort of “Third-party.” An island is part of the world and the world is part of a universe. The raft, however, is not part of the world.
The last difference that will be addressed will be the fact that you can choose to occupy the raft or the island, but you don’t get a choice in occupying the Earth or not.