Subtracting different columns from different rows

Here is an example of how to do this in Power Query. You can do it in DAX, but it is much more involved.

let
    Source = 
    Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("fYyxCcAwDARXEaoNlj4KCr+K0f5rGBJjkibFNcf9j6GRCHNoU+/oMIR48nS6fdy1ndxUe29lsXsYD2PYT/v0sf6dSAJaNQE=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"Ticket ID" = _t, #"Created Time" = _t, #"Submitted Time" = _t, #"Approved Time" = _t, #"Shipped Time" = _t]),
    #"Changed Type" = 
    Table.TransformColumnTypes(
        Source,
        {
            {"Ticket ID", Int64.Type}, 
            {"Created Time", type datetime}, 
            {"Submitted Time", type datetime}, 
            {"Approved Time", type datetime}, 
            {"Shipped Time", type datetime}
        }
    ),
    #"Grouped Rows" = 
    Table.Group(
        #"Changed Type", 
        {"Ticket ID"}, 
        {
            {"_nestedTable", each _, type table [Ticket ID=nullable number, Created Time=nullable datetime, Submitted Time=nullable datetime, Approved Time=nullable datetime, Shipped Time=nullable datetime]}
        }
    ),
    Custom1 = 
    Table.TransformColumns(
        #"Grouped Rows", 
        {
            {"_nestedTable", each Table.FirstN(Table.FillUp(_, {"Created Time", "Submitted Time", "Approved Time", "Shipped Time"}), 1)}
        }
    ),
    Custom2 = 
    Table.TransformColumns(
        Custom1, 
        {
            {"_nestedTable", each Table.AddColumn(_, "Time to Submission", each [Submitted Time] - [Created Time], type duration)}
        }
    ),
    Custom3 = 
    Table.TransformColumns(
        Custom2, 
        {
            {"_nestedTable", each Table.AddColumn(_, "Time to Approval", each [Approved Time] - [Submitted Time], type duration)}
        }
    ),
    Custom4 = 
    Table.TransformColumns(
        Custom3, 
        {
            {"_nestedTable", each Table.AddColumn(_, "Time to Shipment", each [Shipped Time] - [Approved Time], type duration)}
        }
    ),
    #"Expanded _nestedTable" = 
    Table.ExpandTableColumn(
        Custom4, 
        "_nestedTable", 
        {"Created Time", "Submitted Time", "Approved Time", "Shipped Time", "Time to Submission", "Time to Approval", "Time to Shipment"}, 
        {"Created Time", "Submitted Time", "Approved Time", "Shipped Time", "Time to Submission", "Time to Approval", "Time to Shipment"}
    ),
    #"Changed Type1" = 
    Table.TransformColumnTypes(
        #"Expanded _nestedTable",
        {
            {"Created Time", type datetime}, {"Submitted Time", type datetime}, {"Approved Time", type datetime}, {"Shipped Time", type datetime}, {"Time to Submission", type duration}, {"Time to Approval", type duration}, {"Time to Shipment", type duration}
        }
    )
in
    #"Changed Type1"