We all know that guitar strings come in many flavors. They can initially be separated into categories according to what types of guitars they are made for.
There are strings that are designed for acoustic guitars, electric guitars and classical guitars. Within those categories they can be further separated according to thickness (gauge), material, and brand.
Furthermore, each set of strings can be separated into categories of "wound" and "un-wound" strings.
Wound strings are manufactured by "winding" a material around a central core. The result is a "thicker" string capable of producing lower bass tones.
Two common materials that wound strings are made of are "bronze wound" strings, typically found on acoustic guitars – and "nickel wound" strings typically found on electric guitars.
Quite often, the main difference between a set of acoustic guitar strings, and a set of electric guitar strings (other than material); is that an acoustic set contains a wound 3rd string. On an electric set of guitar strings the 3rd string is often un-wound.
A typical set of acoustic guitar strings will usually look like this:
1st (E) – un-wound
2nd (B) – un-wound
3rd (G) – wound
4th (D) – wound
5th (A) – wound
6th (E) – wound
The extra thickness of the wound 3rd on a set of acoustic guitar strings helps add a "fullness" to the tone of an acoustic guitar by increasing the "bottom end" of the sound.
From the perspective of a lead guitarist that plays electric guitar, a wound third string can have a down side. A wound string is much harder to "bend" than an un-wound string.
To prove this to yourself, pick up an acoustic guitar with a wound third and attempt to bend the string. It can be done, but will require a lot of extra finger pressure, and the string will not have as much "give".
This is why most electric guitar sets come with an un-wound 3rd, because so many string bends, when playing lead guitar, take place on the 3rd string.
But ironically there are electric guitar strings available with a wound 3rd string.
Why? Because some electric guitarists that typically play rhythm guitar, prefer the extra "meat" in tone that the wound 3rd string produces.
Which one is best for you? It's hard to say and greatly depends on your personal preference and playing style.
But for the time being, just be aware of the differences between string sets with wound 3rd strings and un-wound 3rd strings, and play around with each until you find the one that works best for you.