As to the role of federal government, Conservatives would say that the founding fathers had it right about the need for government to be limited, and that the Constitution defines the few proper roles of the federal government.
Theoretically (see giant caveats later), conservatives believe that the limits in the Constitution on federal government were met to be limits for all time. Liberals tend to see the Constitution as a document that needs to change with the times - a "living, breathing document."
Conservatives would say that for the most part, individuals, private associations, and the free market can provide. Outside the realm of the Constitution, conservatives would still tend to believe in a smaller local and state government than would liberals.
Some conservative thought says that it is wrong that through taxation, you are being forced to support things monetarily that you may not believe in. Liberals would say that there is a common good that we should all contribute to.
The stereotype is that conservatives want government to leave business (and "the free market") alone, but are busybodies and want government telling you what to do in your private life.
The stereotype for liberals is the opposite - they want government to regulate business more and to stay out of your private life.
(editorial) In reality, liberals are just as likely to tell you what you can and cannot do personally - they believe just as much in taxing or restricting your "sins" as conservatives do. IN fact. liberals are very indignant about a lot of personal behavior they consider "bad" (anti-smoking laws, indignancy about big cars, et cetera). It's just often different behavior than what conservatives believe are bad.
A lot of the reason liberals tend to support taxing personal behavior is because as a rule they are a lot more tolerant of higher taxes - they find them necessary to support everything they'd like the government to do.
Liberals as a rule tend to believe that if there is a problem, there is no reason that the federal government should not try to address it. Conservatives will say "it's not the government's place" and point to supposed Constitutional restrictions or the general concern that government wielding more power will make us less free. Liberals tend to ignore that argument when it comes to the possibility of government addressing "societal problems."
Another big distinction is that conservatives tend to desire defense spending (and military interventionism). Liberals tend to decry military spending and desire "social" spending. But, as can be observed now, liberals in power can end up changing their tune when it comes to war, tending to start marching to the same tune and supporting existing policies.
In practice, "conservatives," for all their "smaller government" belief, don't do much to decrease government spending in Washington. In fact, regarding the federal government, pure "conservative" thought is hardly any different from libertarian thought, in that they both believe the federal government should be restricted in size and scope as defined by the Constitution. Yet, the libertarian party exists and thrives (all things considered), perhaps as a reaction to how little Conservatives, in power, actually do to limit the federal government. Conservatives MAY end up increasing government at a lesser rate than liberals (but even that is quite debatable), but they have a very poor record when it comes to actually decreasing government size, scope, or budget.
(and now.. the editorial)... Just like liberal officeholders, conservatives tend to value getting "free" (emm.. taxpayer) money for their own districts, above and beyond every other goal. When nearly all the congressmen and women, regardless of party affiliation, care more about bringing home federal pork to their districts than they do about... oh.. say.. READING the bills they're foisting upon us, it results in... bigger government (and obviously a bunch of bills that weren't vetted very well, the details of which are ignored, even though they have an effect on Americans).
It is probably true that conservatives are slightly less likely than liberals to "bring home the bacon," but considering their supposed outlook on the size and scope of government, the difference is so slight as to be stark.