In earlier versions of SAS (SAS 5 and 6) PROC MEANS and PROC SUMMARY were separate procedures. Over time, by version 8, the code for the 2 procedures was standardized and "melded" together. There are essentially no differences except that MEANS creates output in the LISTING window or other open destinations, while SUMMARY creates an output dataset by default.
Some more differences
- If you don't mention the VAR statement, PROC SUMMARY produces a simple count of observations. But PROC MEANS analyzes all the numeric variables that are not listed in the other statements.
- If you print the data created by PROC SUMMARY, you'll get _TYPE_ column along with the other descriptive statistics.
- In PROC MEANS, number of records is N whereas it is denoted by _FREQ_ in PROC SUMMARY
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The output can differe when using multiple CLASS variables as well. The output dataset for PROC SUMMARY will resemble the "printed" output for PROC MEANS only when the NWAY option is used. Otherwise you get all of those values for each level of _TYPE_ which is not the default behavior of MEANS.