"Bowle" is a cold, aromatic mixed drink, usually based on white wine. One example is the woodruff-flavoured "Maibowle".
The white wine is often infused with juice, sparkling wine or other spirits. In many cases, aromatic fruits are added to the drink, which can then contain a large part of the alcohol after the appropriate contact time. The punch is usually poured from a wide-mouthed vessel into drinking cups with a ladle.
"Maibowle" was developed as early as the 19th century. "Bowle" itself enjoyed great popularity as a party drink, especially during the 1950s to 1970s.
In contrast, hot mixed drinks made from alcohol, fruits or spices and served in a bulbous vessel are called punch in German-speaking countries. This is why the "Feuerzangenbowle" (known in Germany from the famous film with Heinz Rühmann) is actually not a "bowle", but a punch.
In non-German cultural circles, no distinction is usually made between "bowle" and punch. Those who remember the series "Bonanza" may remember that the Cartwright family likes to serve punch at their parties. But the punch served there is a cold drink and would therefore be a "bowle" in German-speaking countries.
Now there is only one question: If you are in Germany and your punch is getting cold, will it automatically turn into a "bowle"?