On macOS (Darwin, 4.4BSD derivative), you have this nifty process manager called launchd controlled by launchctl analog to systemd and systemctl.
Executing launchctl alone yields a list of subcommands. Among them are bootstrap and load. What is(are) the difference(s) between them?
Subcommands: bootstrap Bootstraps a domain or a service into a domain. bootout Tears down a domain or removes a service from a domain. enable Enables an existing service. disable Disables an existing service. uncache Removes the specified service name from the service cache. kickstart Forces an existing service to start. attach Attach the system's debugger to a service. debug Configures the next invocation of a service for debugging. kill Sends a signal to the service instance. blame Prints the reason a service is running. print Prints a description of a domain or service. print-cache Prints information about the service cache. print-disabled Prints which services are disabled. plist Prints a property list embedded in a binary (targets the Info.plist by default). procinfo Prints port information about a process. hostinfo Prints port information about the host. resolveport Resolves a port name from a process to an endpoint in launchd. limit Reads or modifies launchd's resource limits. runstats Prints performance statistics for a service. examine Runs the specified analysis tool against launchd in a non-reentrant manner. config Modifies persistent configuration parameters for launchd domains. dumpstate Dumps launchd state to stdout. dumpjpcategory Dumps the jetsam properties category for all services. reboot Initiates a system reboot of the specified type. bootshell Brings the system up from single-user mode with a console shell. load Bootstraps a service or directory of services. unload Unloads a service or directory of services. remove Unloads the specified service name. list Lists information about services. start Starts the specified service. stop Stops the specified service if it is running. setenv Sets the specified environment variables for all services within the domain. unsetenv Unsets the specified environment variables for all services within the domain. getenv Gets the value of an environment variable from within launchd. bsexec Execute a program in another process' bootstrap context. asuser Execute a program in the bootstrap context of a given user. submit Submit a basic job from the command line. managerpid Prints the PID of the launchd controlling the session. manageruid Prints the UID of the current launchd session. managername Prints the name of the current launchd session. error Prints a description of an error. variant Prints the launchd variant. version Prints the launchd version. help Prints the usage for a given subcommand.