Design Showing Perfectly in Android Studio Preview but Not in Real Device

I am working on an Android Application and I am trying to implement Design Layout in Android Studio like Image in Android Studio Preview

But When I run It on Real Device It is showing layout like Design In Real Device.

In the Android Studio I used Nexus 4 to design the Layout and my Phone Resolution is 720x1280. Here is my xml code

<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.usmanali.childsafety.MainActivity">

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="275sp"
    tools:ignore="MissingConstraints"
    tools:layout_editor_absoluteX="0dp"
    tools:layout_editor_absoluteY="3dp">

    <ImageView
        android:id="@+id/imgschool"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@drawable/im"
        android:contentDescription="@string/todo" />
</LinearLayout>
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="115sp"
    tools:ignore="MissingConstraints"
    tools:layout_editor_absoluteX="0dp"
    tools:layout_editor_absoluteY="278dp">
    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:src="@drawable/download" />
</LinearLayout>

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="110sp"
    tools:layout_editor_absoluteX="0dp"
    tools:layout_editor_absoluteY="393dp"
    tools:ignore="MissingConstraints">

    <Button
        android:id="@+id/btnlogin"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@+id/btnregister"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:text="@string/login"
        android:textStyle="bold"
        tools:ignore="MissingConstraints"
        tools:layout_editor_absoluteX="0dp"
        tools:layout_editor_absoluteY="291dp" />

    <Button
        android:id="@+id/btnregister"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:text="@string/sign_up"
        android:textStyle="bold"
        tools:ignore="MissingConstraints"
        tools:layout_editor_absoluteX="0dp"
        tools:layout_editor_absoluteY="340dp" />
</RelativeLayout>

Try this

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">


    <LinearLayout
        android:id="@+id/mainLinearLayout"
        android:layout_width="match_parent"
        android:layout_height="275sp"
        tools:ignore="MissingConstraints"
        tools:layout_editor_absoluteX="0dp"
        tools:layout_editor_absoluteY="3dp">

        <ImageView
            android:id="@+id/imgschool"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="@drawable/im"
            android:contentDescription="@string/todo" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/linearLayout"
        android:layout_width="match_parent"
        android:layout_height="115sp"
       app:layout_constraintTop_toBottomOf="@+id/mainLinearLayout"
        tools:ignore="MissingConstraints"
        tools:layout_editor_absoluteX="0dp"
        tools:layout_editor_absoluteY="278dp">

        <ImageView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:src="@drawable/download" />
    </LinearLayout>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="110sp"
        app:layout_constraintTop_toBottomOf="@+id/linearLayout"
        tools:layout_editor_absoluteX="0dp"
        tools:layout_editor_absoluteY="393dp"
        tools:ignore="MissingConstraints">

        <Button
            android:id="@+id/btnlogin"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_above="@+id/btnregister"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true"
            android:text="@string/login"
            android:textStyle="bold"
            tools:ignore="MissingConstraints"
            tools:layout_editor_absoluteX="0dp"
            tools:layout_editor_absoluteY="291dp" />

        <Button
            android:id="@+id/btnregister"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true"
            android:text="@string/sign_up"
            android:textStyle="bold"
            tools:ignore="MissingConstraints"
            tools:layout_editor_absoluteX="0dp"
            tools:layout_editor_absoluteY="340dp" />
    </RelativeLayout>
</android.support.constraint.ConstraintLayout>