以下是Oracle JDBC官方文档的说法：
也就是随便翻译一下就理解了。
JDBC Thin for All Platforms
classes12.jar (1,600,090 bytes) - for use with JDK 1.2 and JDK 1.3
在低级JDK版本1.2与1.3中使用的驱动，虽然实际上在1.4，1.5中使用大部分情况也是OK的
classes12_g.jar (2,044,594 bytes) - same as classes12.jar, except that classes were compiled with "javac -g" and contain some tracing information.
添加了编译调试信息的classes12.jar
classes12dms.jar (1,607,745 bytes) - same as classes12.jar, except that it contains additional code`to support Oracle Dynamic Monitoring Service.
添加了支持Oracle动态检测服务的classes12.jar
classes12dms_g.jar (2,052,968 bytes) - same as classes12dms.jar except that classes were compiled with "javac -g" and contain some tracing information.
添加了支持Oracle动态检测服务与编译调试信息的classes12.jar
ojdbc14.jar (1,545,954 bytes) - classes for use with JDK 1.4 and 1.5
在高级JDK版本1.4与1.5中使用的驱动
下面三个同classes12.jar的情况
ojdbc14_g.jar (1,938,906 bytes) - same as ojdbc14.jar, except that classes were compiled with "javac -g" and contain some tracing information.
ojdbc14dms.jar (1,553,561 bytes) - same as ojdbc14.jar, except that it contains additional code`to support Oracle Dynamic Monitoring Service.
ojdbc14dms_g.jar (1,947,136 bytes) - same as ojdbc14dms.jar, except that classes were compiled with "javac -g" and contain some tracing information.
orai18n.jar (1,645,114 bytes) - NLS classes for use with JDK 1.2, 1.3, 1.4, and 1.5. This jar file replaces the old nls_charset jar/zip files.
ons.jar (48,492 bytes) - for use by the pure Java client-side Oracle Notification Services (ONS) deamon.
demo.tar (604,160 bytes) or demo.zip (529,267 bytes) - contains sample JDBC programs.
