In Jain Dharma, this is usually a custom-based rule, not a strict universal scriptural rule.

• Wall vs door: In many families, a door is treated as part of the sacred threshold of the home or temple space, so people avoid touching it during menstruation.
• A wall is often not given the same ritual importance, so touching it may be allowed.
• In Jain tradition, the main idea is shuddhi (cleanliness) and maryada (discipline), especially around mandir, puja, and sacred items.

So the difference is usually because:

1. Door/threshold is considered more ritually sensitive.
2. Wall is not always seen as sacred in the same way.
3. Different Jain families and communities follow different local customs.

Importantly, this is not one single rule for all Jains. Some follow stricter practices, and some follow gentler household traditions.

If you are following family tradition, the safest approach is to respect that rule.