我个人并没有发现什么大的区别，但也许这两者之间隐藏着什么？
源代码如下

package org.koin.androidx.viewmodel.ext.android

/**
 * Fragment extension to help for Viewmodel
 *
 * @author Arnaud Giuliani
 */
inline fun <reified T : ViewModel> Fragment.sharedViewModel(
    qualifier: Qualifier? = null,
    noinline owner: ViewModelStoreOwnerProducer = { requireActivity() },
    noinline parameters: ParametersDefinition? = null,
): Lazy<T> {
    return viewModel(qualifier, owner, parameters)
}

package androidx.fragment.app
/**
 * Returns a property delegate to access parent activity's [ViewModel],
 * if [factoryProducer] is specified then [ViewModelProvider.Factory]
 * returned by it will be used to create [ViewModel] first time. Otherwise, the activity's
 * [androidx.activity.ComponentActivity.getDefaultViewModelProviderFactory](default factory)
 * will be used.
 *
 * ```
 * class MyFragment : Fragment() {
 *     val viewmodel: MyViewModel by activityViewModels()
 * }
 * ```
 *
 * This property can be accessed only after this Fragment is attached i.e., after
 * [Fragment.onAttach()], and access prior to that will result in IllegalArgumentException.
 */
@MainThread
public inline fun <reified VM : ViewModel> Fragment.activityViewModels(
    noinline extrasProducer: (() -> CreationExtras)? = null,
    noinline factoryProducer: (() -> Factory)? = null
): Lazy<VM> = createViewModelLazy(
    VM::class, { requireActivity().viewModelStore },
    { extrasProducer?.invoke() ?: requireActivity().defaultViewModelCreationExtras },
    factoryProducer ?: { requireActivity().defaultViewModelProviderFactory }

)