Two of the main Norwegian dialects are the western and eastern. The eastern dialect is spoken in the capital Oslo and the western in Bergen, the second largest city of Norway. These dialects exhibit a number of differences in grammar, vocabulary and pronunciation. I wish to focus on pronunciation.
One difference between the two dialects is with respect to pitch. This is a feature which Norwegian shares with Swedish. Disyllabic words with identical pronunciation are distinguished by pitch alone. The two types of pitch are called Tone 1 and Tone 2. For example, the word bønder (farmers) has Tone 1 and bønner (beans) has Tone 2. The two words sound otherwise alike because the "d" of bønder is not pronounced.
However, the two dialects have different types of pitch. The eastern Norwegian dialects have a low-tone accent and the western Norwegian dialects have a high-tone accent.
The eastern Norwegian dialects are called low-tone accents because they have a low flat pitch on the first syllable of tone 1 followed by a rising pitch on the second. Tone 2 has a high falling pitch on the first syllable and a low pitch at the beginning of the second.
The western Norwegian dialects are called high-tone accents because they have a high pitch on the first syllable of tone 1 followed by a low pitch at the beginning of the second. Tone 2 has a rising pitch on the first syllable and a falling pitch at the beginning of the second.
The liquids are also pronounced differently in the two dialects. The lateral of words such as tolv (twelve) and hals (throat) is velarized in the eastern Norwegian dialects but not in the western ones. The rhotic sound of tre (three) and rot (root) is an alveolar trill in the eastern Norwegian dialects but a uvular trill or fricative in the western ones. In words such as først (first) and norsk (Norwegian) the eastern Norwegian dialects have a retroflex alveopalatal fricative but the western Norwegian dialects have a uvular followed by an alveolar fricative.
In words beginning with sl-, the western Norwegian dialects pronounce them as in English. The eastern Norwegian dialects, however, pronounce the "s" as a retroflex alveopalatal fricative. This is also the case when the two letters occur across syllable boundaries. This sound can be heard in words such as slott (castle) and also veksle (to exchange).
Another difference between the eastern and western Norwegian dialects is the pronunciation of the diphthong found in words such as vei (way) and hei (hi). In the dialects of eastern Norway, the diphthong is similar to that of the diphthong in words such as "why" and "my." In western Norway, the diphthong is similar to that heard in words such as "way" and "may."
The two most widely-spoken dialects of Norway, the western and eastern, have many differences in grammar and vocabulary. However, they also have well-known pronunciation differences. As a result, Norwegians can easily identify speakers of these two dialects.