请看HELP OR MANUAL

三者的主要区别就在于所绘图形的精度存在明显差异，其它还存在性能上的差别、用法上的难易程度不同

The plot is a text base version, gplot is graphic version. You may overlay multiple graphes in a single graph.

Sgplot does much more when you have multiple graphes to plot.


Here is from online help.

Overview
The SGPLOT procedure creates one or more plots and overlays them on a single set of axes. You can use the SGPLOT procedure to create statistical graphics such as histograms and regression plots, in addition to simple graphics such as scatter plots and line plots. Statements and options enable you to control the appearance of your graph and add additional features such as legends and reference lines.

The SGPLOT procedure can create a wide variety of plot types, and can overlay plots together to produce many different types of graphs. Examples of Graphs that Can Be Generated by the SGPLOT Procedure contains some examples of graphs that the SGPLOT procedure can create.

Examples of Graphs that Can Be Generated by the SGPLOT Procedure  The following code creates an ellipse plot:
proc sgplot data=sashelp.class;
  scatter x=height y=weight;
  ellipse x=height y=weight;
run;


The following code creates a horizontal box plot:
proc sgplot data=sashelp.cars;
  hbox weight / category=origin;
run;


The following code creates a graph with two series plots:
proc sgplot data=sashelp.electric(
     where=(customer="Residential"));
  xaxis type=discrete;
  series x=year y=coal;
  series x=year y=naturalgas / y2axis;
run;


The following code creates a graph with a histogram, a normal density curve, and a kernel density curve:
proc sgplot data=sashelp.class;
  histogram height;
  density height;
  density height / type=kernel;
run;


The following code creates a graph with two bar charts:
proc sgplot data=sashelp.prdsale;
  yaxis label="Sales" min=200000;
  vbar country / response=predict;
  vbar country / response=actual
                  barwidth=0.5
                  transparency=0.2;
run;

sgplot是在SAS9.2版本及以上才能实现的高分辨率图，是SAS9.13后新加的功能