The concept, for this discussion, is the same. It's a matter of in-person (at school) learning vs. remote (home school or online) learning, dependent on how the school district has approached this school year (mandated at-school, mandated remote, or a parental option).
That is the driver behind whether or not extracurricular activities are being held (or are even allowed to be held) in any given district.
There is a difference. Home schooling is a parent decision. School Districts are making the decision to go 100% online, 50/50 hybrid or 100% in school. What is driving the school districts decision? The level of Covid outbreak in the community AND/OR the districts ability to keep kids safe in schools.
In the case of Ames the districts decision is based on the spike of Covid in the community. In the case of Des Moines school district, it might be more of the later (keeping kids safe).
But regardless of the reason, school board leaders have decided to go 100% online to because of the perceived high risk for community spread in their school district.
So if there is a high risk of community spread in DM or Ames, why would a school district want to expose students from another school district to their Community Spread issues. Whether it is sports, show choir, debate, etc.
IMO it is different if a family chooses the 100% online choice vs. the district. In those cases the family is making a decision to go online because of specific family circumstances. Maybe a grandparent lives with them or a family member has a pre-existing condition that makes them at risk for Covid. It is then that families decision to not allow their children to play sports or other activity participation to protect family members.