You can buy SoftBank telecom suscriptions and services [1], with its trademark, while e.g. Berkshire don't sell soft-drinks (Berkshire has Coca-Cola stock, but it is not Cola-Cola). So, in my opinion, it is not the same thing. Not even close.
You can buy Berkshire Hathaway real estate services, with its trademark. Their logo appears on signs outside private homes for sale all over the place.
Sure, the point is what is their core business. E.g. Sony core business is electronics, despite having financial, entertainment, and other branches. Same thing for SoftBank: yes, it is a holding, but its main business is telecommunications.
Specifically the two ends of the market; direct-to-consumer insurance (GEICO) and insuring things no-one else can, particularly reinsurance and muni debt (Berkshire Hathaway Assurance, Gen Re).
If you're good at writing insurance it's essentially a great way of getting interest-free loans which they then spin into a huge pile of low-risk, cash-generating businesses (e.g. Duracell, Fruit of the Loom, See's Candies, to pick three Berkshire brands...).
I think that's more of a branding thing.
Telecom is just one of the things SoftBank does and it just happens to be more visible to consumers.
Berkshire owns Geico but you wouldn't call Berkshire a insurance company.
