I consider to use SDPX headers in stead of the full license headers in my code. However, I wonder whether this is actually legally equivalent. 

So, for context, this is the SDPX license list: https://spdx.org/licenses/

The header of my code would then not look like this:
```
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
# 
#  http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.
```
but like this:
```
# SPDX-License-Identifier: Apache-2.0
```

I can't really find anything on the web page of SDPX on this. The license header is pretty obvious in stating the main terms and conditions of the license, in a human readable way, while SDPX defines a key one can use to refer to a license, but then you have to know the convention.
 
So I could imagine they may be  legally different.  I know there is no such thing as international copyright law, but it would be useful to have an idea why those are or are not equivalent and what typically differences would be. Would there?

Of course, this is all apart from having a LICENSE file shipped with the code, and probably other requirements that are put on my code if I want to correctly use SPDX.