Ndubuisi 'Andy' Egwim explains why government bonds are safer than other bonds: governments can print money to repay debt, so you won't lose your principal. The tradeoff is inflation risk instead of default risk.
So when it comes to bonds, there are different issuers that can issue bonds. The sovereign bonds are usually the safer ones, basically because they are backed by the country. So if the UK government is owing money, a US government, basically the government is backed by the government, military mind and treasury and whatever they have that they should be able to pay you back. The worst case scenario, they just print some more money. And obviously when they print money, inflation goes up, but they can pay you back. Don't lose money. This is the game here, don't lose money.
