Hi:
Proc Tabulate only produces summary reports, based on class and analysis variables. These summary reports are always tabular in structure, with 3 possible dimensions -- page, row and column dimension.
Proc Report produces both "detail" and summary reports. A detail report is a report where one report row represents one observation from the input data set. A summary report is a report where one report row represents a group of observations. Both detail reports and summary reports can have inter-group or overall report summary lines added to the report.
For example, if you have 100 employees spread across 3 states and 5 departments, a report that listed each employee and their salary would be a DETAIL report. It would have at least 100 report rows if you picked all employees. On the other hand, a summary report of average salaries for each state would NOT have 100 report rows -- it would only have 3 report rows -- one for each state. Or if you summarized by STATE and DEPARTMENT, you might have one row for every unique combination of STATE and DEPARTMENT, but not more than 15 (3 states *5 departments), unless you added summary rows (total for each state, total for each department or overall total) to the report.
There are too many features of each procedure to list here. It takes a 3 day class to provide thorough coverage of ODS, PROC TABULATE and PROC REPORT. I suggest you take some familiar data and experiment with REPORT versus TABULATE syntax. Or, you can search for more papers like these:
http://www2.sas.com/proceedings/sugi27/p133-27.pdf
http://www2.sas.com/proceedings/sugi28/071-28.pdf
http://www.scsug.org/SCSUGProceedings/2007/papers/how/HOW-Winn.pdf
http://www2.sas.com/proceedings/sugi30/258-30.pdf
http://www2.sas.com/proceedings/sugi24/Handson/p153-24.pdf
cynthia