This may differ from one company to another. But they include:
Short-term assets include things like cash, accounts receivable, inventory, and prepaid expenses. These items are relatively easy to convert into cash, so they're considered more liquid than long-term assets, which are hard to sell off quickly.
Long-term assets include land, buildings, machinery/equipment, intangible assets like patents and trademarks, and other investments that can't be turned into cash quickly.