たこ焼きはソースで食べるけど明石焼きはスープで食べます。って英語でなんて言うの？

Sometimes people get confused with different foods from different countries so you might have to explain to them how to eat it correctly to get the best taste
so you could say 'you eat Takoyaki with sauce and akashiyaki with soup'

"Normally" is used when we want to say that something is done generally, as a rule, or under normal conditions.
If something is customary it means that it is quite common in a certain area. For example "bowing" is very customary in Japan as it is done all the time when meeting people. Using this word "customary" is a great way of emphasising the fact that this is very commonplace

The difference is that takoyaki is eaten with sauce whereas akashiyaki is eaten with soup. - "the difference" is a phrase we can use to say that two or more things are different in these ways. Other variations are "what's different is...".

You eat takoyaki with sauce and akashiyaki with soup - this is explaining how you eat something, by saying "you eat...".

When explaining the difference between "takoyaki" and "akashiyaki". you want to say that takoyaki is eaten with sauce but akashiyaki is eaten with soup. See the above possibilities with this statement.

To talk about two things and the differences between them we use the phrase 'the difference between (item one) and (item two) is...
Then after, state what the difference is:
Takoyako is eaten with sauce but akashiyaki is eaten with soup.
This phrase is used often when talking about differences in detail.

This sentence is explaining that the food "Takoyaki" is to be eaten with sauce (a special condiment which will cover the food) and "Akashiyaki" is to be eaten with soup (a type of meal that is boiled with water and many other ingredients).
'Opposed' Is used for describing two different things which may conflict with each other.