I've heard of "health sharing" before as an alternative to health insurance. Is this the same thing?

"Health sharing" is not health insurance and can be dangerous to consider as similar.  In concept, "health sharing" members choose to pay an agreed upon dollar amount, and those funds are aggregated for the group.  Then, payments are distributed from this aggregated total to health providers for the expenses of each member.  If a member has a more serious medical need (e.g., cancer treatment), it could be expensive and drive up the cost for all members.  There is little to no regulation, and costs can vary depending on the members' needs.  If a need is greater than the funds collected, there is no way to pay for your healthcare needs through the "health sharing" and the individual is responsible for the amount due. 

With traditional health insurance, regulators closely watch the relationship between premiums, claims being paid, and surplus to pay outstanding claims.  It's safer and better regulated.  Trusting a "sharing" membership to make the most important decisions for your family, with no oversight, can be ill-advised and financially devastating.