Is algebra harder than calculus

No calculus is harder, because calculus is basically a combination of algebra and trigonometry, so you need algebra to do calculus.

Also, calculus involves limits, differentiation, and integration. Integration makes algebra look like kindergarten.

+++

Meaningless question, ditto with the answers I'm afraid. These are not separate entities but all fields of mathematics, and you use algebra in expressing and solving mathematical problems. Calculus is NOT "basically a combination of algebra and trigonometry". You can differentiate and integrate trig. functions, but although calculus alone does not rely on trigonometry for its existence, its manoeuvres are all algebraic steps.

As to comparative difficulty, that is entirely down to you. If you find algebra difficult you will find trigonometry and calculus difficult, because algebra is used to describe those two (and any other) mathematical process. Algebra is not an isolated topic!