This is the distinction between a first language ("mother-tongue") and a secondary, acquired language. As usual, however, the disitnction can often be problematic. To begin with, "mother-tongue" is OK for the majority of people whose mothers speak the same language as they do, but this doesn't have to be the case. A child of, say, Vietnamese parents who came to Iceland early in the child's life will probably have Icelandic as their* L1, and perhaps speak Vietnamese badly or not at all. And an Icelandic child who was born abroad and moved home to Iceland when they were 6, 10 or even later, may have originally had Swedish or Luxembourgish as their L1, but speak better Icelandic by the time they're 20.
For this course, we'll make some simple distinctions.
L1 is the language a person learns before they learn to read and write. It's quite possible to have more than one L1, even three or four. When a person learns to read and write their L1, they learn how to use an alphabet to represent the words in their minds, but this representation isn't only dependent on the sound of the word - an English-speaking child, for instance, learns that the same sound-shape can be spelt differently depending on its meaning - as for instance 'son' and 'sun' (both ), and 'write' and 'right' (both )
In this course, we'll use the term "L2" to mean a language learnt in school or as part of an educational program. An L2 is almost always learnt at the same time as its writing-system, and very often learnt by means of its writing-system. If you've learnt English this way, you'll probabaly have come to the conclusion that words such as 'son' and 'sun' or 'write' and 'right' are pronounced differently - they look very different, and it's easier to remember their spelling if we make a distinction in pronunciation also. This is called SPELLING PRONUNCIATION, and it is one of the strongest characteristics of the pronunciation of Icelandic students in my classes, and probably of a very large proportion of people throughout the world who speak English as their L2.
So here's a typical test question:
Look up words such as 'correspondence' and 'importance' in a good pronunciation dictionary such as Wells's Longman Pronunciation Dictionary, and you should see the answer to this question. And while you're about it, look up the words 'Korea' and 'career' and see if you can find any difference in their pronunciation!
Can you explain why a native RP-speaker might make spelling mistakes like "correspondance" while an L2-speaker of English is less likely to make this mistake?