A cushion is foundation in a portable compact, usually dispensed through a sponge or mesh and applied with a puff. A bottle gives you more freedom to dispense foundation onto your hand, a brush or a sponge. That difference changes how you carry and apply it. It does not tell you, by itself, how much coverage you will get or whether the finish will be matte.
If you want one compact for your bag and quick touch-ups, a cushion makes sense. If you like controlling the amount you dispense and changing tools for different finishes, a bottle is often the easier starting point. Choose the formula after deciding which routine you actually prefer.
A cushion is not automatically a light, dewy foundation
Korean cushions cover quite different looks. HERA Black Cushion is presented as a soft satin base, while Jung Saem Mool Essential Skin Nuder Cushion is described as dewy with buildable coverage. Both are cushions. The compact does not put them in the same finish category.
The same applies to bottles: a liquid can be sheer, dense, glowy or relatively matte. Buying a bottle because you assume it will cover more can leave you with a skin tint when you wanted a fuller base. Buying a cushion because you assume it will look invisible can be just as disappointing.
Read the finish and coverage description, then look at the exact shade and product version. Even closely named products within one brand can behave differently. TIRTIR shade codes can help narrow the options, but a good match in one line does not mean another will look identical.
What the compact makes easier
A cushion keeps the foundation, applicator and mirror together. That is useful when you are getting ready away from home or carrying a small bag. You can pick up a little product and press it onto a specific area without finding a separate brush.
The tradeoff is that pressing harder can load the puff with more foundation than you intended. Start with a light press and tap the puff against the dispensing surface or inner lid where the product design allows it. Apply a thin layer first, then add coverage to the areas that still need it.
Touch-ups need a little judgement. If your nose is oily and the existing base has moved, simply pressing fresh foundation over everything can make it look heavier. Gently remove excess oil and smooth the disturbed area before adding a small amount. A compact makes that possible on the go; it does not make every extra layer look fresh.
What a bottle makes easier
With a bottle, you can dispense a small amount and see how much you are using before it touches your face. You can spread the base with a brush, press it in with a suitable sponge, or use clean fingers if the formula works well that way.
That flexibility is useful if you want more coverage around the centre of the face and less at the edges. You do not have to apply the same amount everywhere. A little concealer on a persistent mark may also give a cleaner result than another full layer of foundation.
The less convenient part is carrying the rest of the routine. A bottle alone may not help much in a café bathroom if the mirror and applicator are at home. A brush or sponge also needs somewhere clean to travel and dry after washing.
Compare the amount you actually receive
Some cushions include a refill; others do not. The JSM listing above explicitly excludes a refill, whereas the HERA listing describes a compact-and-refill configuration. Those are different packages, so the price on the front is not enough for a fair comparison.
Compare the included grams or millilitres, the refill arrangement and the cost of the next purchase. Also consider whether you are likely to use the formula before replacing it. A larger bottle is not better value if the shade is wrong and it stays untouched.
Keep the puff clean, let it dry fully after washing and close the compact properly. The convenient packaging still needs care. A dirty applicator is not a reason to abandon cushions altogether, but it is part of the routine you are choosing.
Which would I choose?
For a simple portable base, I would start with a cushion in the finish and shade I wanted. For applying makeup mainly at home, especially if I already liked a brush or sponge, I would compare bottled formulas just as seriously.
Neither choice requires a second foundation for completeness. Pick the format you will enjoy using, then judge the actual product on coverage, shade and how it wears on your skin.