If you compare it to a regular home coffee machine the Rancilio contains more metal. The portafilter (the thing with the handle that contains the basket where the coffee grinds are put) is the same as their shop grade machines. It's big and heavy and feels solid like it'll last a long time. While if you compare the portafilter of a regular home coffee machine they often feel cheap and flimsy. The switches on the front feel industrial too. With the exception of a few bits (as noted in the article) the exterior is mainly stainless steel. While other home coffee machines at similar price point (and above) are far more plasticy.
The Siliva is often a good introduction for home coffee enthusiasts and hardware hackers alike. They're often recommended on coffee snob forums as a result. They're fairly ubiquitous so getting parts is straight forward. IIRC The manual contains circuit diagrams. It's easy to open and tinker with too. The most common modification is adding a PID controller to regulate the temperature.
The machine itself is straightforward but fills a niche. The next level up of more expensive home enthusiast machines generally cost at least twice the price. The next level up of coffee machine generally includes a PID and often twin boilers, so you can use one boiler for shots and the other boiler to foam milk. While with the Siliva as it's only got a single boiler you have to do your shots first, then switch it over to steam mode.
If you look after Siliva it can last for 10 years or more (I've had mine that long and it's still going on). I really want a duel boiler machine, but I'm trying to figure out which ones are good at the moment.
It'd say a Delonghi with similar specs is aimed at someone more causal. The kind of audience George Clooney is targeting with Nespresso. While the Siliva is not aimed at someone who just wants a coffee. You have to learn how to make decent coffee and for that it needs to be paired with a good grinder.