It will depend on what version of Word you have. If it's Word 2000 or above,
you can change the table wrapping to Around, which will allow you to put
tables side by side. If they need to be very close, you'll need to tinker
with the "Distance from text" settings.

Often, however, this is the least satisfactory method, since wrapped objects
of any kind can cause problems. Other solutions are:

1. Put the tables in newspaper-style columns (one in each); the columns can
be uneven to accommodate tables of different width.

2. Create a single large table with an empty (and unbordered) column between
the two pieces. This will work only if the row height is the same in both
tables (though you may be able to get around that by selectively merging
cells vertically).