No. An HOA has power over you. A neighborhood union gives you power over external parties through strength in numbers.

HOA will complain you have trash on your lawn. A neighborhood union can help you take on the waste management company that keeps half ass emptying your cans and leaving the remainder blowing in the wind.

An HOA will fine you for having the police show up at your house repeatedly. A neighborhood union can help you push back against police harassment.

An HOA will tell you you can't plant veggies in your yard. A neighborhood union can join together to coordinate planting, tools, and other resources that could reduce the blight of grass farming.

An HOA is usually a compulsory organization with obligatory fees acting as a layer of government without the usual methods of redress when it's out of line. A neighborhood union is a voluntary organization created to serve a common good.