is any card that produces mana a land?

[Jolkor]

Hello, am new to magic and was wondering if all cards that make mana are lands

or more specifically,

can Arbor Elf untap Llanowar Elf?

Can I find Llanowar Elves using Boundless Realm?

do I count Llanowar Elves for Bountiful Harvest?

thanks

[Arix]

No. Mana and lands are two different things. Being able to produce mana doesn't make something a land.

[Kenji]

Something is a land only if one of the following is true:

1. It has "land" in its type line,
2. Its rules text specifically says that it's a land, and/or
3. An outside effect causes an object to become a land.

As Arix pointed out, a permanent that produces mana is not automatically a land -- unless one of the above is true.

Llanowar Elves is not a land. Dryad Arbor is a land (and a creature simultaneously - an extremely rare feat). Again, checking the type line is the easiest way to determine this.