Is 240 mhz better than 120 mhz?

MHz (Megahertz) is used to measure several different things, so it depends on the context.

• In radio transmission, neither frequency is used by most consumers (120 Mhz is in the air traffic band, 240 MHz is used by military aircraft). Since both are used for voice transfer (as opposed to data), neither one is "better" for that purpose.
• In microprocessors, MHz refers to the number of cycles a processor completes each second. If all other things about the two processors are equal, the 240 MHz one will be faster. This number cannot be used to compare two dissimilar processors, however, such as an Intel Pentium and a Motorola 68060.