Now as far as askAlexa versus AlexaHelper…
@MichaelS can say more precisely as he is the author of both. But here’s how I explain it (and he can correct me if I’m wrong):
AlexaHelper: Echo still just does on and off, but AlexaHelper can tie a virtual switch to almost any SmartThings event, including mode changes, routines, etc
Alexahelper is the older one. It was created to make it really easy to set up virtual switches that echo would recognize that could be tied to all kinds of events in SmartThings, like running routines. And people started asking for more and more features, like timers and multiple events and I don’t even remember what all. But it grew over time. It assumed that you would be using the official SmartThings/echo integration, and you just wanted an easy way to set up several virtual switches so the echo could turn the virtual switches on and off and smartthings can run various different events.
AskHome, an Alexa Skill for programmers who wanted to work with SmartThings
Later, one of the other community members created an Alexa skill which would allow technical community members who were willing to sign up for an Amazon developers account and write their own code a way to have echo do things which are much more complex than the official integration allowed for. For example you could ask which doors were left open.
Michael was inspired by this and went on to create “askAlexa,” which is code which will allow you to implement this kind of integration somewhat more easily. I don’t want to go into a lot of technical details about it, but there are a lot of technical details, and they are very well documented in the community created wiki:
So… Alexa helper is a fairly complex smart app but it runs entirely within the SmartThings environment, and it’s really just a way of tying virtual switches to various SmartThings events so that you can use those on/off switches with the official SmartThings/echo integration. It doesn’t require any programming. The installation is a little bit complicated, but not bad, and again entirely within the SmartThings environment.
Ask Alexa is something altogether different. It is actually code, part of which will run within the Amazon environment, which is why you will need an Amazon developer account. With it you will be able to make echo do things that normally it is not capable of. You’ll also be able to go beyond the official SmartThings/echo integration. It is very powerful, but it does require some programming, and it is quite complex.
My short answer would be that Alexa helper lets you use the official smart things/echo integration more easily to control most SmartThings events. And ask Alexa changes the nature of the SmartThings/echo integration and extends the features that are available so that you can have echo do things that it normally does not.
But again, Michael can say more.