What is the difference between "would visit" and "would be visiting?"

Question

What is the difference between these two:

I am busy tomorrow. If I had time, I would visit my grandparents.

I am busy tomorrow. If I had time, I would be visiting my grandparents.

Answer 1

The second example is an example of "progressive" or "continuous" form: to be + -ing form of verb.

Simplifying, this form is used to indicate something happens over a length of time rather than talking about when it started, or something that only happens at a point in time.

It can also be used as a logical "stretch" when the speaker/writer wants to communicate that something is in progress or not yet complete.

Non-continuous form doesn't necessarily imply the opposite, though.

I am busy tomorrow. If I had time, I would visit my grandparents.

Means that if the speaker/writer had time, he/she would visit his/her grandparents sometime tomorrow. No implication as to how much of the day that would take.

I am busy tomorrow. If I had time, I would be visiting my grandparents.

Means any of:

• If the speaker/writer had time, he/she would spend the whole day visiting his/her grandparents

• Or at least spend a significant length of time from that day visiting.

• Or the act of visiting his/her grandparents would take a significant length of time and he/she would dedicate part of the day to it. For example, it may take several hours to travel there and/or back.

Answer 2

I am busy tomorrow. If I had time, I would visit my grandparents.

I am busy tomorrow. If I had time, I would be visiting my grandparents.

Both have mixed tenses which may be hampering your comprehension.

The first "I am" is present tense, singular, but is referring to an event in the future (tomorrow).

I will be busy tomorrow.

Would make more sense.

The second sentences of both examples also differ in their tenses, example 2, uses the present continuous be visiting with the past tense would, would being the past tense of will.

See here: When should I use would, would-be, will and will have? (ELU)

In summary both examples, are a complete mishmash of tenses, so to compare meanings would be an exercise in futility.