Can you explain(Japanese)?

Question:

What is the difference between Ta form+ ra for the expression of "If" and the Jouken form?

Ame ga futtara,telebi o mimasu
If its raining,i'm watching TV

Ame ga fureba,telebi o mimasu
If it's raining,i'm watching TV

Answer:

- futtara, ....shi-masu
- fureba, ....shi-masu

I don't think there's much difference here. But we say;
- ameno hi wa terebi o mimasu. (I watch TV on a rainy day./ I watch TV when it rains)
--> for describing your 'habit'
- ame ga futtara/fureba, sore wa chuushi to narimasu. (If it rains, it will be cancelled)
--> a typical jouken form.

*When you have a certain plan to do, but there's another option, you're supposed to use 'condition'.
On this matter, watching TV is not really a good phrase for 'jouken' form.