It would be easy to say yes they are the same thing, and you will find them used interchangeably because arguably the difference is only a virtue of the language or words used rather than the intended meaning.
In many ways they are the same and for most projects they will indeed amount to the same thing, however, User Centered Design should be considered to be a subset of Human Centered Design.
Human Centered Design has ISO Standards:
ISO 9241-210:2010: Ergonomics of human-system interaction -- Part 210: Human-centred design for interactive systems
ISO 9241-210:2010 provides requirements and recommendations for
human-centred design principles and activities throughout the life
cycle of computer-based interactive systems. It is intended to be used
by those managing design processes, and is concerned with ways in
which both hardware and software components of interactive systems can
enhance human–system interaction.
Human-system interaction. That doesn't necessarily mean 'users' per-se, although it might well include users. It doesn't necessarily include computers or devices in the sense of a physical device with keyboard and/or screen.
The System could be built into the environment, a piece of architecture, a workplace, or an inanimate product. People may not use the product in the way you and I use a website or smartphone, but they still interact with it.
Outside of this ISO standard, non-computing based products can still be considered under the umbrella of human or user centered design.
In Don Norman's The Design of Everyday Things, he talks about Human Centered Design and development whilst discussing things like light switches, doors, taps (faucets) and other physical devices that are not computer based. These things still have users, but at some point to call those people 'users' starts to become a bit of a stretch - so you enter the realm of Human Centered Design, and that's where you start to think in terms of 'designing for people' as opposed to 'designing for users'.