There are many different types of keyboards available. On the lower end are keyboards that you’d find in a toy store, while music stores have keyboards that are more fully-featured and intended for serious musicians and producers. These types of keyboards are commonly loaded with different voices, tones, rhythms, and sound effects to give a player or producer a lot of control over their sound. Within this type of keyboard, you’ll find synthesizers and MIDI controllers. Another differentiator among keyboards is the number of keys. Some keyboards have fewer than the traditional 88 keys you’d find on a digital piano. This allows certain keyboards to be more compact and generally doesn’t impact the ability for the player to create music. While some keyboards have keys that are weighted, many do not. This means that keyboards do not move or react like piano keys.
Many basses have just one pickup, typically a "P" or "MM" pickup, though single soapbars are not unheard of. Multiple pickups are also quite common, two of the most common configurations being two "J" pickups (as on the stock Fender Jazz), or a "P" near the neck and a "J" near the bridge (e.g., Fender Precision Bass Special, Fender Precision Bass Plus). A two-"soapbar" configuration is also very common, especially on basses by makes such as Ibanez and Yamaha. A combination of a J or other single-coil pickup at the neck and a Music Man-style humbucker in the bridge has become popular among boutique instrument builders, giving a very bright, focused tone that is good for jazz, funk and thumbstyle.
Finally, the last but not the least, you need to consider the price of the guitar when purchasing a bass guitar. Before setting your foot in the store, you need to set a budget in your mind for how much you want to spend. As a beginner, you will probably want to take a look at the entry level models. You can pick up one that sounds quite nice for under $500. If you are still uncertain whether you want to make it a full-time commitment to playing the bass, try to look for a cheaper model. A decent guitar can be had for around $200. Try not to be tempted by some shiny, more expensive models as they are beyond your skill level at this point may be. You can always buy something more advanced and high quality when you get better in your bass guitar training.
Specific bass brands/models became identified with particular styles of music, such as the Rickenbacker 4001 series, which became identified with progressive rock bassists like Chris Squire of Yes, and Geddy Lee of Rush, while the StingRay was used by funk/disco players such Louis Johnson of the funk band The Brothers Johnson and Bernard Edwards of Chic. The 4001 stereo bass was introduced in the late 1960s; it can be heard on the Beatles' "I Am The Walrus." 
Like the Casio, the Yamaha has a duet mode that allows two people to play in the same register at the same time. However, the P-45 has only one headphone output, so you’ll need a splitter for both players to use headphones while playing together. The headphone jack is located on the back panel of the keyboard, making access a bit more difficult than with the Casio’s front-mounted jacks. The console controls are minimal, and while Jack liked the simplicity, Brent and I found them unintuitive.
No matter which digital piano you choose, you're in for something special. The instruments found on these pages all offer different features, so take a few minutes to think about your needs as a musician and go from there. Whether you go with a higher-end stage piano like the top-selling KAWAI MP11 Professional Piano or a student model Yamaha's NP12 61-Key Entry-Level Piaggero Ultra-Portable Digital Piano, any digital pianos here will enhance your musical journey.