Of course there r some differences ….
<b>SYS:</b> All of the base tables and views for the database’s data dictionary are stored in the schema SYS. These base tables and views are critical for the operation of Oracle. To maintain the integrity of the data dictionary, tables in the SYS schema are manipulated only by Oracle; they should never be modified by any user or database administrator, and no one should create any tables in the schema of the user SYS. The default pass is change_on_install
<b>SYSTEM:</b> The SYSTEM user name creates additional tables and views that display administrative information, and internal tables and views used by Oracle tools. Never create in the SYSTEM schema tables of interest to individual users. SYSTEM is a little bit “weaker” user than SYS, for example, it has no access to so called a$ tables. Although in real life u may be in a situation when some product or whatever u want to create objects in above mentioned user’s schemas. The default pass is : manager.
In one sentence it may be defined as
SYS is the data dictionary owner and SYSTEM is intended for database administration.