A lawyer covers a number of legal professionals.
Solicitors do more day to day ground work on more general legal matters and some court work.
They will retain the services of a barrister(s) for certain court work as they can only represent their clients up to a certain level.
There is also the significant amount of non-contentious work in areas such as property, wills, probate.... anything which hasn't got any kind of argument to it if that makes sense.
Barristers do higher up court work (there are certain rights of audience in different courts) and are more expert in their knowledge of certain parts of the law. They also give a lot of advice (opinion) on legal matters to solicitors, especially as to what the most likely outcome at court (or tribunal etc...) would be.
If legal action is anticipated, it is common to get counsel's opinion from a barrister as to the likelihood of success based on their more expect knowledge and experience.
The work of individual lawyers can be completely different though. I'm a solicitor and my job is very different to that of many other solicitors, there is such a large diversity of practice areas and much more specialisation these days. You don't get so many of the high street family lawyers who do a bit of everything and there is a significant commercial legal world out there.
Hopefully Barmaid will see this as she is a barrister so can give you her slant on it :)