The simplest way to show a contrast between two (or more) ideas is to use the co-ordinating conjunction "but". Note that both Finnish and English agree that you should put a comma before the 'but' when the second sentence has a separate subject.

DIFFERENT SUBJECTS: use a comma

However, if both sentences have the same subject (compound subject), English tends to delete the second subject, and no comma therefore need be placed before the "but". (See also Using the comma with 'coordinating conjunctions').

SAME SUBJECTS: no comma

"But": Focus

Although the simplest way to show a contrast between two (or more) ideas is to use "but", it tells the reader nothing about which of the two clauses is more important, the first or the second. Moreover, overusing "but" can make your writing sound naive and even childish. Which clause should receive focus?

These schemes provide a solution to current traffic problems, but they are difficult to implement in their present form.

Notice how using subordinators, sentence connectors, and prepositions allows the writer to shift the focus (shown in bold) to different parts of the sentence.

These schemes provide a solution to current traffic problems. However, they are difficult to implement in their present form.

These schemes are difficult to implement in their present form. Nevertheless, they do provide a solution to current traffic problems.

Although these schemes provide a solution to current traffic problems, they are difficult to implement in their present form.

These schemes provide a solution to current traffic problems, even though they are difficult to implement in their present form.

These schemes provide a solution to current traffic problems. However, they are difficult to implement in their present form.

Despite difficulties in implementing these schemes in their present form, they do provide a solution to current traffic problems.

"But": Style

Although you may frequently see in magazines and newspapers sentences beginning with "but", this is not considered appropriate style in academic writing. Do not begin a sentence with "but" in academic writing. Instead, choose from a variety of contrastive sentence connectors.

Technically, it would be possible for America to use more coal instead of oil. There is enough coal in the United States to power America’s electrical plants for another 250 years. But burning coal releases greenhouse gases that cause global warming.

Technically, it would be possible for America to use more coal instead of oil. There is enough coal in the United States to power America’s electrical plants for another 250 years. However, burning coal releases greenhouse gases that cause global warming.

Use "yet" like "but" to contrast two complete clauses (subject + verb). When used in this way as a co-ordinating conjunction, always separate "yet" from the first clause with a comma. Although close in meaning to the sentence connector "nevertheless", "yet" is clearly more informal than "nevertheless" and is punctuated differently: unlike most sentence connectors, no comma is placed after "yet" to separate it from the sentence subject.

To combine two full clauses (subject + verb), you generally use the conjunctions "or", "but", or "and" separated from the first clause by a comma.

positive ( + ) positive ( + )

We still need to determine whether this warming proves the validity of the climate models.
We still need to determine whether this warming disproves the validity of the climate models.

Although the warming observed is consistent with an enhanced greenhouse effect, we still need to determine whether this warming proves the validity of the climate models, or whether it disproves the models.

However, when combining two negative clauses, use "nor" before the second clause (not "or", "but", or "and"):

Negative ( - ) Negative ( - )

It does not prove the validity of the climate models.
It does not disprove the models.

Although the warming observed is consistent with an enhanced greenhouse effect, it does not prove the validity of the climate models, nor does it disprove the models.

Note that in these constructions nor causes an inversion of the auxiliary verb and the subject. The affirmative order "they are..." (subject-before-verb) is reversed in the negative form "nor are they..." (verb-before-subject).

Negative ( - ) Positive ( + )

	1	2
These schemes are not technically compatible with the present system, but	they	are	easy to implement
in their present form.

Negative ( - ) Negative ( - )

	2	1
These schemes are not technically compatible with the present system, nor	are	they	easy to
implement in their present form.

However, when a verb is negated by not or never, and is followed by a negative verb (but not an entire clause), you can use either "or" or "nor":

 

Verb phrases:	He will not / never permit the change or / nor even consider it.
	(1 subject, 2 verbs)
Full clauses:	He will not permit the change, nor will he even consider it.
	(2 subjects, 2 verbs; note also the use of a comma!)

 

When noun, adjective, or adverb phrases are introduced by "no" or "not", the use of "nor" is optional, though "or" is actually more common than "nor".

Typically, “nor” is used together with “neither” to form neither...nor (ei... eikä myöskään), the negative equivalent of either...or (singular) and both...and (plural).

Use ”albeit” to concede, give, or admit facts that either change or reduce the effect of something mentioned earlier in the same sentence. The actual meaning of ”albeit” is closer to 'even though’, ”even if”, ”in spite of this” or ”although (it be so)”, and just like though, it can be placed after the main clause to concede or admit the existence of other facts that might change the reader’s "rosey" interpretation.

Although the conjunction "albeit" can join clauses (subject + verb), it usually joins noun phrases, adverbs, adjectives, and other parts of speech. Further, "albeit" usually introduces a negative fact in opposition to the positive claim made in the main clause.

See also "albeit"  vs. "notwithstanding"