is there actually a difference between BTD4 and BTD4 Expansion

[path]

they have different version numbers, copyright dates, and menu layouts, but otherwise i cannot notice a difference, both have the dartling gun and spike factory included, what is the difference between these two versions?

[Revalopod]

btd4 expansion has a couple new maps maybe?

[GoldGleam]

BTD4 Expansion has a few more maps than base BTD4, and buying the last unlock rank gets you one further than base BTD4.