The EU has got a number of different legislative instruments that it uses.
A Regulation is (referring to your question) analogous to an Act of Parliament. Regulations are EU wide laws which directly take effect in all EU countries.
A Directive is a piece of legislation that sets out a goal which all member states have to comply with. Directives are not laws that directly take effect, but the member states have to pass their own laws in order to comply with the directive.
A Decision is binding to those who it is addressed to. I guess this is most closest to Statutory Instruments as related to your question.
A Recommendation is a non-binding proposal about what member states or their institutions should do.
An Opinion is a non-binding way for EU institutions to make their stand point known.
Depending on the instrument and legal area different processes take effect to pass the legislation. Most common is that the Commission makes a proposal and the council and parliament have to vote by majority in favor.
As to size, scope and frequency. EU Regulations are the most powerful pieces of legislation in the EU. Therefore they generally have a bigger scope and lower frequency, because in most cases Council, Parliament and Commission have to agree on a common piece of legislation.